Colloquial suffix that attaches to nouns, adjectives, and verbs to express resemblance or similarity. Functions as a na-adjective.
He is innocent like a child.
He's just like a child.
This dish tastes sort of Italian.
It's hot like summer today, isn't it?
It seems like it's raining.
This doll looks just like the real thing.
そう and みたい both express 'looks like', but みたい is more casual and can attach to nouns directly, while そう attaches to verb/adjective stems.
foolish; stupid; ridiculous; absurd
Developed as a colloquial shortening of expressions based on 見たよう, “appearing as if seen,” especially 見たようだ. It became an adjectival expression marking resemblance or inference.