We've all been overwhelmed with work, or seen an underwhelming movie but it occurred to me that i've never heard anyone use the root word, whelm. Whelm (verb) 1. I am confused about when to use finish instead of complete and vice versa.

What are other idioms or expressions for the phrase i can't wrap my head around?. But what i still can't wrap my head around is why she behaved like that