Indissoluble

Part of speech: adjective (a.)

1. Not dissoluble; not capable of being dissolved, melted, or liquefied; insoluble; as few substances are indissoluble by heat, but many are indissoluble in water. Boyle.

2. Incapable of being rightfully broken or dissolved; perpetually binding or obligatory; firm; stable, as, an indissoluble league or covenant. To the which my duties Are with a most indissoluble tie Forever knit. Shak.