Merriam-Webster Collegiate Dictionary - en-

 I. prefix  also em-  Etymology: Middle English, from Anglo-French, from Latin in-, im-, from in  1. put into or onto enthrone ; cover with enshroud ; go into or onto enplane — in verbs formed from nouns  2. cause to be enslave — in verbs formed from adjectives or nouns  3. provide with empower — in verbs formed from nouns  4. so as to cover enwrap ; thoroughly entangle — in verbs formed from verbs; in all senses usually em- before b, m, or p  II. prefix  also em-  Etymology: Middle English, from Latin, from Greek, from en in — more at in in ; within enzootic — usually em- before b, m, or p empathy