Intimate
Friendly, Close
い adjective
This is a single kanji with some kana and an い on the end, meaning you know it's probably an adjective. What's the adjective form of intimacy? It's intimate! Depending on the context, this also means friendly or close.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you:
Those who are most intimate with you hang out with you even when you're doing gross things, like sitting on the sh*tter (した). Gross, your family is.
まだ親しい友人にしか話してないの。
I've only told this to close friends.
大学生の時に親しかった先生に、道でバッタリ会ったんです。
I ran into a teacher who I was close with in college on the street.
いくら親しいからって、トイレに入ってきちゃダメだよ。
No matter how close you are, you shouldn't come into the bathroom.