The act of giving a kiss.
"The children were excited about the tradition of kissing on New Year's Eve to bring good luck."
present participle of kiss
"The children spent their afternoon kissing on the porch swing."
In plain English: Kissing is when two people press their lips together gently, usually to show affection or love.
"She was kissing her baby goodnight before bed."
That kisses.
"The toddler's constant kissing on his grandfather's cheeks made him feel like an old man again."
The word "kissing" comes from the Old English verb cyssende, which meant "kiss." It traveled into Middle English as kissynge and eventually became the modern form we use today to describe the act of kissing.