En-

CIDE DICTIONARY

En-,  

•  A prefix signifying in or into, used in many English words, chiefly those borrowed from the French. Some English words are written indifferently with en-or in-. For ease of pronunciation it is commonly changed to em-before p, b, and m, as in employ, embody, emmew. It is sometimes used to give a causal force, as in enable, enfeeble, to cause to be, or to make, able, or feeble; and sometimes merely gives an intensive force, as in enchasten. See In-.  [1913 Webster]
•  A prefix from Gr. in; as, encephalon, entomology. See In-.  [1913 Webster]

OXFORD DICTIONARY

En-, prefix (also em- before b, p) forming verbs, = IN-(1):
1 from nouns, meaning 'put into or on' (engulf; entrust; embed).
2 from nouns or adjectives, meaning 'bring into the condition of' (enslave); often with the suffix -en (enlighten).
3 from verbs: a in the sense 'in, into, on' (enfold). b as an intensive (entangle).

En-, prefix (also em- before b, p) in, inside (energy; enthusiasm).

Etymology

Gk