We found one dictionary that defines the word one's heart in one's mouth:

General (1 matching dictionary)

1. one's heart in one's mouth: Wiktionary

Definitions from Wiktionary (one's heart in one's mouth) ▸ noun:  (idiomatic) A state of dread. ▸ Words similar to one's heart in one's mouth ▸ Usage examples for one's heart in one's mouth ▸ Idioms related to one's heart in one's mouth ▸ Wikipedia articles (New!) ▸ Words that often appear near one's heart in one's mouth ▸ Rhymes of one's heart in one's mouth ▸ Invented words related to one's heart in one's mouth