Originally meant
From Old French rejoir, literally 'to gladden greatly, give joy again,' built from re- 'again, back, intensively' + joir 'be glad,' from Latin gaudere 'to rejoice'; the word passed into Middle English from Anglo-French.
Background
It appears in Middle English in the 13th century, first often in the transitive sense 'make glad.' It is related to Old French joie and ultimately to Latin gaudium 'joy' and gaudere 'be glad.'