This is the 2316th most frequent Japanese word.
こい
"こい" can mean "love" or "carp" depending on the context.
Here, "こい" (濃い) describes the intensity or depth of feelings, referring to a strong emotional bond.
彼のこい友情は感動的です。
His deep friendship is touching.
In this sentence, "濃い" means "rich" or "strong" and is used to describe the intensity of flavor in food.
彼は濃い味の料理が好きです。
He likes rich-flavored dishes.
In this context, "こい" (深い) can figuratively refer to a deep area, often associated with water or spaces.