be unfamiliar with, have little knowledge of
音楽に疎いね
You don’t know much about music.
— 最強のふたり (2011)
トムはスポーツには疎い。
Tom doesn't know much about sports.
僕は最近の情勢に疎い。
I'm not very familiar with recent developments.
貴様は階級に疎いな
You don't know much about ranks, do you?
— 続・夕陽のガンマン (1966)
音楽もユーモアも―両方に疎いね
You're clueless about both music and humor.