a crush on

a Determinative

— A is used when the following word could be any of a certain type. Compare "A book I saw on the shelf" and "The book I gave you yesterday".

a Noun

— A is the first letter of the alphabet. The letter "a" comes before "b". — In some schools, an A is a very high grade. Ron got an A on his earth science test.

crush Verb

— To damage something by flattening it. I will crush the spider with a book.

crush Noun

— If you have a crush on someone, you like them and want to date them. This could be because you think they are attractive. I've got a crush on Joey, but you can't tell anyone. — The person you have a crush on is called a crush. Cindy was my boyhood crush.

on Preposition

— positioned at the upper surface of, touching from above The apple is on the table. — at the date of Tim was born on the 4th of July. — along, forwards (continuing an action) drive on, rock on — about, dealing with the subject of I have a book on history. There was a World Summit on the Information Society a few weeks ago. — touching; hanging from I have no money on me at the moment. I would like to eat the fruit on the trees. — because of, due to He was arrested on suspicion of bribery. I contacted Joanne on a hunch that she would know about it. The stock price increased on news of a new product.

on Adjective

— If something is on, it is active, functioning or operating. The television is on. The lights are on, so it is very bright.