精通 せいつう
seitsū

Noun
Suru Verb

1. being well versed (in); being well acquainted (with); being familiar (with); having a thorough knowledge (of); being an authority (on)

Intransitive
かれ英語 えうご精通 せいつうしている。
karewa ēgoni sētsū shite iru.
He is quite at home in English.
Noun
Suru Verb

2. (a boy's) first ejaculation; spermarche; semenarche

Intransitive