1620s, "university degree of a bachelor," from Modern Latin baccalaureatus, from baccalaureus "student with the first degree," alteration of Medieval Latin baccalarius "one who has attained the lowest degree in a university, advanced student lecturing under his master's supervision but not yet having personal licence" (altered by folk etymology or word-play, as if from bacca lauri "laurel berry," laurels being awarded for academic success).
The Medieval Latin word is of uncertain origin; perhaps ultimately from Latin baculum "staff" (see bacillus), which the young student might carry. Or it might be a re-Latinization of bachelor in its academic sense.
In modern U.S. usage, baccalaureate usually is short for baccalaureate sermon (1864), a religious farewell address to a graduating class at an American college, from the adjectival sense "pertaining to the university degree of bachelor."
