7 letters · 15 points in Scrabble
noun a loud kiss
noun a very powerful blow with the fist
originFrom smack + -er. In reference to lips, from the sound of a loud kiss. In reference to money, cf. ackers (influenced in part by the smacking sound that is sometimes produced when cash is transferred from the hand of one person to the hand of another, or placed onto a hard surface such as a table or counter).
Etymology from Wiktionary, CC BY-SA 3.0