sunsick Share definition Flag Just like homesick, sunsick is the definition of someone missing the sun. During winter or on a cloudy day, you would use this expression. :) -Look dude, its raining. I think I'm sunsick..-I miss the sun too, dude.. sunsick by NatheKat June 1, 2009 0 0 Get merch Get the sunsick mug. Buy Now — $32.95 See more merch