1530s, "make into an island," from Latin insulatus, from insula (see insular). Sense of "cause a person or thing to be detached from surroundings" is from 1785. Electrical/chemical sense of "block from electricity or heat" is from 1742. Related: Insulated; insulating.
1848, "act of making (something) into an island," noun of action from insulate. Transferred sense attested by 1798. Electrical sense is from 1767. The concrete sense of "insulating material" is recorded by 1870.
