/ ˈmɔɪstʃə(r); NAmE / noun
[ U ] very small drops of water that are present in the air, on a surface or in a substance :
the skin's natural moisture
a material that is designed to absorb / retain moisture
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WORD ORIGIN
late Middle English (denoting moistness): from Old French moistour , from moiste , based on Latin mucidus mouldy (influenced by musteus fresh, from mustum , neuter (used as a noun) of mustus new).