GCSE Chemistry

What is a dilute acid?

Acid = a proton (H+) donor (Brønsted-Lowry definition) – i.e. it loses H+ in solution, meaning that the solution is acidic.

Dilute is a description of how concentrated the solution is.
Think about a glass of squash or cordial. If it is very dilute, there will be a lot of water in it, and not very much fruit juice. If it is very concentrated, there will be a lot of fruit juice, and not very much water.
Same goes for acids and bases. If A is more dilute than B, then a given volume of A will have more H2O molecules than B, and fewer acid particles than B. And vice-versa for being more concentrated (= less dilute).

A handy page: https://www.chemguide.co.uk/14to16/acidmenu.html