end-

• endo-
• ento-

From the Ancient Greek ἔνδον (éndon, “within”).

• (Received Pronunciation) enPR: ĕnd, IPA^(key): /ɛnd/

end-

1. internal, within, inside, into

• When combined with a term beginning with a consonant, end- concatenates with the interfix -o- (as endo-).
• The prefix end- is usually stressed in the terms it forms (as in endoscope: ĕnʹdōskōp); however, it is never stressed when stress falls on the following syllable (as in endoscopy: ĕndŏʹskŏpi), and stressing the prefix is optional when the subsequent syllable is stressed (as in endoscopic: ĕndōskŏʹpĭk or ĕn'dōskŏʹpĭk).

• (inside): in-, intra-, en-/em-/im-, endo-/ento-

• (antonym(s) of “inside”): out-, ex- exo-, ecto-

• “endo-, prefix” listed in the Oxford English Dictionary, second edition (1989)

• DEN, DNE, Den, Den., NDE, NED, Ned, den, edn., ned