before vowels thalass-, word-forming element meaning "sea, the sea," from Greek thalassa "the sea" (in Homer, when used of a particular sea, "the Mediterranean," as opposed to ōkeanos), a word from the Pre-Greek substrate language. In Attic Greek thalatta, hence sometimes thalatto-.
Thaddeus
Thai
Thailand
thalamus
thalassemia
thalasso-
thaler
Thalia
Thalidomide
thallium
thallus