1. n. an event during the 1960s where one or more couples made love in a public place. My uncle was at one of those love-ins, and he said if anything was going on, it was going on under blankets.
2. n. an event in the 1960s where everyone became euphoric—with the help of marijuana—about love and respect for their fellow humans. Everyone at the annual company love-in was throwing love bombs around at each other.