What do you call it when you use on sence to describe another? (like this sounds soft + sweet, or looks loud)?

Question

onomatopia is when you describe something with the way it sounds

(like meow or mooo not actual adjectives that describe senses)

Answer 1

What you are looking for is metaphor. Something described as if it was another, unrelated, subject. x is a y. My love is a rose. ...my winged thought...

Metaphor was a Greek word meaning "transfer". The Greek etymology is from meta, implying "across," and pherein meaning "to bear, or carry".

Synesthesia is the actual condition where two of a persons senses correspond to a single stimulus. Such a person has colored hearing or shaped taste.
Colored hearing is when the individual listens to music and sees the music as colored shapes. Thus the metaphors (e.g., "loud shirt", "bitter wind" or "prickly laugh") are sometimes described as "synesthetic".

Answer 2

onomatopoeia