from The American Heritage® Dictionary of the English Language, 4th Edition
- Inside; within: endometrium.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- end- + -o-
from the GNU version of the Collaborative International Dictionary of English
- A combining form signifying within.
from The Century Dictionary and Cyclopedia
- A prefix in words of Greek origin, signifying ‘within,’ ‘inside’: equivalent to ento-: opposed to ecto- or exo-, and in some cases to apo-, epi-, and peri-.
Greek, from endon, within; see en in Indo-European roots.(American Heritage® Dictionary of the English Language, Fourth Edition)