Latin will keep you compos mentis

What does it mean?Joules solemn under the oak

To be compos mentis is to be of sound mind. It’s basically a fancy way of saying ‘I’m/he’s/she’s sane/sober/calm.’


Compos mentis is an adjective that translates literally to ‘in command of one’s mind.’ It first came into use in the English language in the early 17th century, around 1610.

Improper Use

Not to be confused with the opposite non compos mentis, meaning ‘not of sound mind.’ Both terms are generally used in the legal or medical profession, in the former when one tries to explain their behaviour with outlandish excuses they genuinely believe, and the latter when a patient is being assessed on whether or not they can make their own decisions about the healthcare and treatment they receive.

Proper Use

Outside of a legal and medical context, compos mentis can also be used metaphorically (which is how it is used in the examples below) however like many Latin terms is rare in informal use. Examples of use in a sentence include:

After studying for the big test, Bob felt that he was no longer compos mentis.
She was so drunk at the party she could no longer be considered compos mentis.

Ante bellum

What does it mean?884064

Ante bellum means the period before a war. The accepted usage of the term, usually written as antebellum, refers to the American South before the civil war.


The term literally translates to English as ‘before the war.’ It came into English language usage in the late 19th century.

Improper Use

One might argue that using ante bellum to define any period other than the one it traditionally refers to is improper. The country music group Lady Antebellum have received criticism about their choice of name, with people calling it inappropriate and even racist.

Proper Use

Examples of use in a sentence include:

Many Antebellum Mansions in Nashville are now open to the public for use for events such as weddings.
Gone with the Wind was written about life in the antebellum south.

Find this lesson in situ…

What does it mean?865092

In situ is a fairly daunting and complicated Latin term that is not commonly seen in colloquial use. It is usually taken to mean ‘in its original place.’ It is used in many different fields, such as archaeology, economics and literature.


The literal translation of in situ from Latin to English is ‘in place’ (although some will argue it means ‘in position.’) It can be used as both an adjective and an adverb. Its first recorded use was said to be around 1740.

Improper Use

Despite accepted use in numerous professions, the term in situ has not yet found its way into informal use. This is not to say it would be incorrect, nor is it strictly unacceptable, should it be used in the right sentence or context; just that it isn’t ever really seen.

Proper Use

In situ is used in different situations and contexts for a variety of different professions, but always translates to the same meaning of ‘in place/position.’ Examples of use in a sentence include:

‘The fossil was found in situ.’

(Archaeology: The term used here means that what was uncovered was found in the original position that it was made or deposited.)

‘Bob undertook his testing in situ.’

(Psychology: Meaning that the subject of an experiment was located outside of a laboratory or usual work setting at the time, i.e. at the workplace.)

Persona non grata

What does it mean?625022

To declare somebody persona non grata is to state that they are ostracised or unwelcome. It usually means somebody, usually a diplomat, is forbidden by the government from entering or staying in a certain country. It can also be used in a non-diplomatic context to refer to somebody who has been shunned by a group of people for whatever reason they see fit.


‘Persona non grata’ is a Latin term, literally translating to ‘person not acceptable,’ is a Latin term which is neither part of the classical nor New Latin language. It has, however, been in use since as early as the 15th century.

Improper Use

When pluralised, persona non grata is sometimes erroneously written as personas non grata. This is incorrect; the plural version of the term should be written as personae non grata, as within Latin.

Proper Use

Persona non grata is used in mostly a formal, legal context, but informal use is not unheard of. Examples of use in a sentence include:

                 “The spies were deported as persona non grata.”
                 “Bob found himself persona non grata at the party after the incident the previous weekend.”

No Latin yesterday… mea culpa.

What does it mean?842022

Mea culpa is the admission or acknowledgement of making a personal mistake. Traditionally, it is used in the prayer The Confiteor in the Catholic Church. It is slowly making its way into contemporary everyday use.


Mea culpa is a Latin term translating literally into English as “through my own fault.” Perhaps because of its use in prayer, the term has been used in English for centuries. The first recorded use was in the late 14th century by Chaucer in Troylus, though it has likely been in use before this.

Improper Use

Some might argue that any use outside of prayer is improper, but as can be seen above, the phrase has been making its way into speech and the written word for hundreds of years. It is perhaps one of the less commonly seen Latin phrases in common or popular use, but, technically speaking, wouldn’t be incorrect or out of place in an informal context.

Proper Use

In a non-religious context, think of mea culpa as a fancy way of saying ‘my bad.’ Like most Latin phrases in English use, it is italicised. It can be used both as a noun and an interjection, although the former is more common. As a noun, it usually refers to a detailed and sincere apology. Examples of use in a sentence include:

“I forgot – mea culpa,” said Bob.
She wrote a long mea culpa on her blog to apologise to everyone she’d hurt.

The phrase can also be extended to mea maxima culpa, literally meaning ‘my most grievous fault.’

On terra firma

What does it mean?Are you coming

Terra firma means ‘dry land.’


Terra firma is a New Latin term literally meaning ‘solid earth.’ It’s first recorded use in the English language was c. 1595-1605.

Improper Use

Terra firma is not used to mean Earth in general, as opposed to space; just dry land, that is, the solid part of the earth.

Proper Use

Compared to other New Latin terms, the use of terra firma is considerably rare, although it is recognisable to many people. Examples of use in a sentence include:

             ‘Bob couldn’t wait to get his feet back on terra firma when his cruise had finished.’
             ‘The sailors returned to terra firma to meet their families after months out in the sea.’

“Ipso facto, I’m your boss…”

What does it mean?653047

Ipso facto is a New Latin term meaning ‘by the nature of the deed’ or ‘by the fact itself.’ It refers to something, for example a penalty, that is a direct consequence brought about by an action or offence. It is not commonly used in everyday speech, and is commonly thought of as ‘jargon’ in law, technology and science.


Ipso facto literally means ‘by that very fact.’ Sources conflict as to its first recorded use in the English language, but sources most commonly point to the mid-16th century. But it has appeared in famous literary works such as Christopher Marlowe’s Dr Faustus.

Improper Use

Ipso facto is sometimes misused, especially in the ‘blogosphere,’ in the place of ‘in fact’; this is understandable, but erroneous.

Proper Use

The term should only be used to describe something that is a direct result of a fact or action. Examples of use in a sentence include:

            ‘Bob turned up to band practise without his guitar, and ipso facto was kicked out.’
‘She talked about herself all the time. Ipso facto, no one liked speaking with her.’

Despite the usage above which were written for the purpose of example only, please keep in mind that ipso facto is still relatively uncommon in informal use.

In Toto… I don’t think we’re in Kansas anymore

What does it mean?643040

The meaning of in toto is ‘totally’ or ‘as a whole.’ It is synonymous with ‘altogether.’


In toto comes from the Latin term ‘totus,’ meaning total.  The term in toto translates literally to ‘in total’ or ‘in entirety.’ Sources conflict as to its first recorded use in English; some claim it was in the 1600s, whilst others state it came into use in the 18th century.

Improper Use

In toto is sometimes erroneously written as en toto. Although ‘en’ does mean ‘in,’ spelling it this way isn’t considered acceptable in modern use.

Proper Use

In toto is generally used in a legal context, and hasn’t yet really found its way into everyday conversation. It is occasionally used outside of the legal profession, mostly in academic works or newspaper articles. Examples of use in a sentence include:

                        ‘Bob’s case was dismissed in toto.’
                        ‘The flood destroyed everything in the basement in toto.’

De facto

What does it mean?674018

De facto is a Latin term which has become part of the English language. It means ‘in reality,’ ‘in practice’ or ‘actually.’ In Australia and New Zealand, it is also a term for ‘common law wife.’


The literal translation of De facto from Latin to English is ‘in fact.’ It is unknown when it first came into use as an accepted part of the English language.

Standard Use

De facto can be used as an adjective, adverb and a noun, and is often used to refer to a practice which is common or accepted, but not officially recognised or legal. Examples of use in a sentence include:

              ‘Bob’s girlfriend was his de facto wife.’
              ‘She’s become a de facto politician in her local community.’

Any Subject et al.

What does it mean?758088

‘Et alia,’ arguably similar to ‘et cetera,’ means ‘and others.’ It is used to shorten a list of people or objects. ‘Et al’ is most commonly used in an academic context.


‘Et alia’ is a Latin term which literally means, as above, ‘and others.’ ‘Et alii’ is the masculine version of this term and ‘et aliae’ the feminine. For example, if your list consists of all males, technically speaking, you would be more likely to use the former, and females the latter. However, it is very rare to see this in use; the term is usually abbreviated to simply ‘et al.’ It first came into use as part of the English language in 1883.

Improper Use

‘Et al’ is not to be confused with ‘inter alia,’ a Latin term meaning ‘amongst other things.’ It is also not to be confused with ‘et cetera,’ although the terms may be construed as similar. See here for our Latin lesson on ‘et cetera.’

Proper Use

Some sources, such as MLA Guidelines, state that it is only acceptable for use when the list consists of a minimum of three people or items. ‘Et alia’ is usually written as the more common abbreviation ‘et al.’  Examples of use in a sentence are as follows.

‘Bob Bobbedo et al. state that Latin is good for you.’
‘Trent Strawberry et al. have pretty weird sounding names.’

As always, make sure you think clearly about what the term actually means in English before you use it.