The Proto-Indo-European word *menkus
Word *menkus
Meaning soft
See also Proto-Indo-European: *menk- ‘to step, tread over, press’
Synonyms *l(e)nto-, *meldh-, *mel(h₁)-

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

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