Definitions

1. adjective

extremely cheesy or clichéd; overly sentimental or sentimental in a way that is considered to be annoyingly or offensively sentimental

“The corniest romantic comedy I’ve ever seen made me roll my eyes.”

2. superlative form of corny

more cheesy or clichéd than corny; more overly sentimental or sentimental in a way that is considered to be annoyingly or offensively sentimental than corny

“He thought the movie was the corniest he’d ever seen, but his friend loved it.”