in ‧ su ‧ la ‧ tor /ˈɪnsjəleɪtə, ˈɪnsjʊleɪtə $ ˈɪnsəleɪtər/ BrE AmE noun [countable]
a material or object which does not allow electricity, heat, or sound to pass through it OPP conductor :
Wood is an excellent insulator.
in ‧ su ‧ la ‧ tor /ˈɪnsjəleɪtə, ˈɪnsjʊleɪtə $ ˈɪnsəleɪtər/ BrE AmE noun [countable]
a material or object which does not allow electricity, heat, or sound to pass through it OPP conductor :
Wood is an excellent insulator.
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012