a decision that what you thought earlier is not true or right now.

He'd been active in the organization for years, but after a change of heart, Yang left the group.

He never wanted a movie made about him, but three months before he died, Chavez suddenly had a change of heart.

• on-the-spot
• on the spot
• on the spur of the moment
• on the starting blocks
• on the strength of
• on the strength of something
• on the stump
• on the table
• on the threshold of
• on the threshold of something
• on the tip of tongue
• on the tip of your tongue
• on the town
• on the trot
• on the verge of
• on the verge of doing something
• on the wagon
• on the warpath
• on the way
• on the whole
• on the wing
• on the wrong side of the law
• on the wrong track
• on thin ice
• on time