The Proto-Indo-European word *mel(h₁)-
Word *mel(h₁)-
Meaning soft
Synonyms *l(e)nto-, *meldh-, *menkus

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

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