adverb, adverb taking the 'to' particle, noun or participle which takes 'suru', noun which may take the genitive case particle 'no'
Describes something applied or decorated in a thick, heavy, or excessive way, often with a negative or exaggerated nuance. Common with makeup, paint, decoration, or flavor.
彼女はコテコテに化粧をしている。
She is wearing thick makeup.
このラーメンはコテコテのこってり味だ。
This ramen has a heavy, rich flavor.
noun which may take the genitive case particle 'no'
through and through; to the core; proper
Used to emphasize that someone or something is thoroughly or completely of a certain type, often in a colloquial or slightly negative way. Common in phrases like コテコテの関西人 (a dyed-in-the-wool Osakan).
彼はコテコテの大阪人だ。
He is an Osakan through and through.
あの店はコテコテの昭和レトロな雰囲気だ。
That shop has a thoroughly retro Showa-era atmosphere.