heart in one's mouth

idiom

Definition of heart in one's mouth

informal

Note: If your heart is in your mouth, you are very excited or nervous about something.

heart play

: a hollow muscular organ of vertebrate animals that by its rhythmic contraction acts as a force pump maintaining the circulation of the blood
: a structure in an invertebrate animal functionally analogous to the vertebrate heart
: breast, bosom

mouth play

: the natural opening through which food passes into the body of an animal and which in vertebrates is typically bounded externally by the lips and internally by the pharynx and encloses the tongue, gums, and teeth
: grimace
: an individual requiring food