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.

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.