An idiom is a phrase where the words together have a meaning that is different from the dictionary definitions of the individual words. It is a natural way of speaking among native speakers which can make
idioms hard for students to understand.

Below are listed some of them in alphabetical order A-Z:

A

A piece of cake: A task that can be accomplished very easily.

Example: ‘The Maths exam was a piece of cake’ (= el examen de matemáticas fue muy fácil).

All Greek to me: Something that is meaningless and incomprehensible to understand.

Example: ‘The exam was all Greek to me’ (=el examen me sonaba a chino).

Apple of my eye: someone who is cherished above all others.

Example: ‘I love her! She is the apple of my eye’. (¡La quiero! Es la niña de mis ojos).

B

Be on the same wavelength: To agree with each other. Thinking the same thing as another person. 

Example: ‘We are on the same wavelength about most of the important issues’. (=Estamos en la misma onda en los asuntos más importantes).

Bite my head off: To speak or reply to someone angrily.

Example: ‘My boss bit my head off yesterday’.(=Mi jefe me contestó muy enfadado ayer).

D

Dropping like flies: A large number of people either falling ill or dying very quickly.

Example: ‘During the war people dropped like flies’. (=Durante la Guerra, la gente caía como moscas).

E

Excuse my French: Please forgive me for cussing.

Example: ‘Excuse my French, but you’re an asshole’. (Perdone, pero usted es un imbécil).

I

In deep water: to be in a very difficult or dangerous situation.

Example: ‘They got in deep water while driving home’.(=Ellos estuvieron con el agua al cuello mientras volvían a casa).

K

Knock on wood:  This phrase is used by people who rap their knuckles on a piece of wood hoping to avoid some bad luck. In the UK, the phrase ‘touch wood‘ is used – often by tapping one’s head, after saying something we don’t want to happen.

Example: ‘I’m the only one in my family who doesn’t have acne. Knock on wood’.(=Soy el único de la familia que no tiene acné. Toco madera).