English Reference

Word

cos

/ˈkɔs/

Definitions

01because

B1

conj. a short way to write or say 'because' in casual conversation.

conj. an informal clipping of 'because', used primarily in spoken English or casual digital communication.

“I didn't go to the party cos I was feeling really tired.”

“He decided to skip the lecture 'cos he'd already covered the material during his summer internship.”

Informal · British English

Usage

Often written with an apostrophe as 'cos to show letters are missing.

Pitfall

I stayed home cos of the rain.

I stayed home 'cause of the rain.

While 'cos' is common in British texting, it is too informal for essays or professional emails; use 'because' instead.

Synonyms

02lettuce

B2 · Cooking

n. a type of lettuce with long, crisp leaves, often used in Caesar salads.

n. a variety of lettuce (Lactuca sativa var. longifolia) characterized by long, narrow, crisp leaves and a firm rib.

“We need to buy some cos lettuce for the salad tonight.”

“The chef prefers using cos for its superior crunch and ability to hold heavy dressings without wilting.”

British English

Usage

Commonly referred to as 'romaine' in American English.

Synonyms

romaine

Real-World Examples

“Everybody protected was important to me, ’cos it’s a life.”
The Guardian · 3 Sept 2026

This entry

Level
B2 · Upper Intermediate
Frequency
Common
Updated

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English Reference