mouthful; morsel; bite
gulp; sip; draft; draught
one word; in short
one share; one contribution
ケーキを一口食べてみた。
I tried one bite of the cake.
水を一口飲んで話を続けた。
I took a sip of water and continued talking.
一口に言えない複雑な問題だ。
It is a complex problem that cannot be summed up in a word.