-oid

WordReference Random House Learner's Dictionary of American English © 2025

-oid, suffix. 

1. -oid is used to form adjectives and nouns with the meaning "resembling, like,'' with the suggestion of an incomplete or imperfect similarity to the root element:
   human + -oid → humanoid (= resembling a human, but not quite the same).

WordReference Random House Unabridged Dictionary of American English © 2025

-oid, 

1. a suffix meaning "resembling,'' "like,'' used in the formation of adjectives and nouns (and often implying an incomplete or imperfect resemblance to what is indicated by the preceding element):
   alkaloid;
   cardioid;
   cuboid;
   lithoid;
   ovoid;
   planetoid.
   Cf. -ode ¹.

• Greek -oeidēs, equivalent. to -o- -o- + -eidēs having the form of, derivative of eîdos form

Collins Concise English Dictionary © HarperCollins Publishers::

-oid suffix:forming_adjectives , suffix:forming_nouns

1. indicating likeness, resemblance, or similarity: anthropoid

Etymology: from Greek -oeidēs resembling, form of, from eidos form