adverb
Definition: In a direct or exact manner; exactly or precisely.
Example: He fell smack on the ground after tripping over the rock.
intransitive verb
Definition: To collide with a loud noise or to make a sharp sound, often used to describe a hit or impact.
Example: The ball smacked against the wall, making a loud noise.
noun
Definition: A sharp blow or slap, often made with the hand, or a noisy kiss.
Example: She gave him a quick smack on the cheek as a greeting.
transitive verb
Definition: To hit someone or something with a quick, sharp motion that makes a loud noise, or to kiss someone noisily.
Example: She gave him a quick smack on the cheek before leaving.