therein \(ˈ) ̷ ̷| ̷ ̷\adverb Etymology: Middle English therin, from Old English thǣrin, from thǣr there + in 1.: in or into that place : in or into that thing < the box and the jewels found therein > 2.: in that particular : in that respect : in such matter < therein our letters do not well agree — Shakespeare >