Heart is a synonym of audacity.
As nouns the difference between heart and audacity
is that
heart is (anatomy) a muscular organ that pumps blood through the body, traditionally thought to be the seat of emotion while
audacity is insolent boldness, especially when imprudent or unconventional.
As a verb heart
is (transitive|poetic|or|humorous) to be fond of often bracketed or abbreviated with a heart symbol.