The Proto-Kartvelian word lumb-
Word lumb-
Meaning wet

Comments
Heinz Fähnrich, Surab Sardshweladse: Etymologisches Woerterbuch der Kartwel-Sprachen, 1995 Brill

Other words that might be of interest
ṭab- ‘lake’, ṭba ‘lake’, zɣwa ‘sea’