thermostable

adjective

Unaffected by relatively high temperatures, as certain ferments or toxins.

Unaltered in composition or activity by a moderate degree of heat: noting especially certain toxins and ferments. Opposed to thermolabilc.

adjective

Capable of being heated to or somewhat above 55° C. without loss of special properties; — said of proteins, immune substances, etc.

adjective

Physically or chemically unaffected by high temperatures