furnace (noun) furnace: heating mechanism
Sinonime: defenseless,
exposed, fluctuant,
frail,
hazardous,
immature,
insubstantial,
loose, open to attack,
perilous, rickety, rocky, rootless, shaky, unguarded, unprotected,
unreliable, unsafe, unshielded, unsound,
unstable, unsteady,
vacillating,
vulnerable,
wavering,
weak, wobbly
Antonime: guarded,
protected,
safe, secure,
sound