Answer:

insulator

Answer	Crossword Clue
INSULATOR	Glass, vis- -vis electricity
INSULATOR	Porcelain, e.g.
INSULATOR	Asbestos, for one

INSULATOR	Asbestos, e.g.
INSULATOR	Glass, at times

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.