Other forms: quelled; quells
Meaning to suppress or overcome, quell is what you have to do with nerves before a big test and fears before going skydiving.
When it first came into existence, the verb quell actually meant “to murder.” That's a bit more serious than our modern definition, but you can use that old definition to help you imagine offing your worries or putting a permanent end to criticism. These days quell is often used to mean "pacify," as in the police quelling an angry mob or a mom quelling a kid's temper tantrum.