humectant
Concise Oxford English Dictionary © 2008 Oxford University Press:
humectant /hjʊˈmɛkt(ə)nt/
▶adjective retaining or preserving moisture. ▶noun a substance, especially a skin lotion or a food additive, used to reduce the loss of moisture.
– origin C19: from L. humectant-, humectare ‘moisten’.
'humectant' also found in these Oxford entries:

