The Proto-Indo-European word *meldh-
Word *meldh-
Meaning weak, soft
See also Proto-Indo-European: *ml̥dho/ehₐ- ‘clay’
Synonyms *hₐepus, *l(e)nto-, *losiwos, *mel(h₁)-, *menkus

Comments
Mallory J.P. and Adams D. (2006)

Other words that might be of interest
*kar- ‘hard’, *k̂leu- ‘hear’, *saiwos ‘hard, sharp, rude’