Middle English, "a person who reaps crops or trims trees," from croppen "to crop entry 2" + -er-er entry 2
Noun (2)
of uncertain origin
Note: The Oxford English Dictionary, first edition, suggests some relationship with the phrase neck and crop "completely, entirely," usually in reference to a fall or to expulsion from a place. Joseph Wright's English Dialect Dictionary records crop in the sense "neck, throat" from a few northern and western locations; presumably this is a sense of crop entry 1. In this event, neck and crop would be a joining of two synonyms. Whatever value these hints have, a full etymology is lacking.