-tomy

1.
a combining form meaning “cutting, incision” of an organ, “excision” of an object, as specified by the initial element (appendectomy; lithotomy); also occurring in abstract nouns corresponding to adjectives ending in -tomous, (dichotomy).
Compare -tome, tomo-, -tomous.
Origin
representing Greek -tomia; see -tome, -y3
British Dictionary definitions for -tomy

-tomy

combining form
1.
indicating a surgical cutting of a specified part or tissue: lobotomy
Word Origin
from Greek -tomia; see -tome
Word Origin and History for -tomy

word-forming element meaning "a cutting," from Greek -tomia "a cutting of," from tome "a cutting, section" (see tome).

-tomy in Medicine

-tomy suff.
Act of cutting; incision: gastrotomy.