Here are some simple answers from a native speaker. Dismiss is to send a person away. "The boat captain dismissed the crew." Discard is to throw an object aside. "I discarded the banana peel." Discharge is to release (usually energy) "The static electricity discharged from my sweater and shocked me." "He was discharged from the army." Disembark is to get off of a ship or plane, etc. "We disembarked at New York." Dismount is to get off of (usually a horse or a vaulting horse). "The cowboy dismounted and shot the bad guys." "The gymnast landed the dismount."

Hi, you can use online dictionaries like www.thefreedictionary.com