"the science of fishes; the department of zoology which treats of fishes," 1640s, from ichthyo- "fish" + -logy. Related: Ichthyologist; ichthyological.
Entries linking to ichthyology
ichthyo-
word-forming element meaning "fish," from Latinized form of Greek ikhthys "a fish" (in plural, "a fish-market"), from PIE root *dhghu- "fish" (source also of Armenian jukn, Lithuanian žuvis).
-logy
word-forming element meaning "a speaking, discourse, treatise, doctrine, theory, science," from Greek -logia (often via French -logie or Medieval Latin -logia), from -log-, combining form of legein "to speak, tell;" thus, "the character or deportment of one who speaks or treats of (a certain subject);" from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')." Often via Medieval Latin -logia, French -logie. In philology "love of learning; love of words or discourse," apology, doxology, analogy, trilogy, etc., Greek logos "word, speech, statement, discourse" is directly concerned.