Meaning of 口火 in Japanese

Definition of 口火

くちび(kuchibi) 【口火】

くちびをきる(kuchibiwokiru) 【口火を切る】

(exp, v5r) to start the debate; to get the ball rolling; to fire the first shot (fig. only); to start a conversation
グループの人たち全員が沈黙しているときは、誰かが話の口火を切らねばならない。
When all the group members are silent, somebody must break the ice.

ジョンは授業中じゅぎょうちゅういつも口火を切るくちびをきる。

John always breaks the ice in class.

When all the group members are silent, somebody must break the ice.

"Let me ask you something, Dad," she began, in a tone of patiently controlled exasperation that every experienced parent is familiar with.