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oral; verbal; spoken; parol
口頭での説明だけでは分かりにくい。
It's hard to understand with only an oral explanation.
契約は口頭でも成立する場合がある。
Contracts can sometimes be established orally.
口頭試問では緊張して上手く話せなかった。
I was nervous during the oral exam and couldn't speak well.