- 1[intransitive, transitive] to become or make something become flat or flatter The cookies will flatten slightly while cooking. flatten something These exercises will help to flatten your stomach. He flattened his hair down with gel. The bird is recognizable by its flattened beak. Roll the dough into balls and flatten slightly.
- 2[transitive] flatten something to destroy or knock down a building, tree, etc. Most of the factory was flattened by the explosion.
- 3 [transitive] flatten somebody (informal) to defeat someone easily in a competition, an argument, etc. Our team got flattened last night!
- 4[transitive] flatten somebody (informal) to hit someone very hard so that they fall down He flattened the intruder with a single punch. I'll flatten you if you do that again! Phrasal Verbsflatten something/yourself against somebody/somethingflatten outflatten somethingout
NAmE//ˈflætn//Verb Forms present simple I / you / we / they flatten
he / she / it flattens
past simple flattened
-ing form flattening