be (as) solid as a rock

To be stable, sturdy, and reliable. They've been married for 50 years, so their relationship has to be solid as a rock. That table must be as solid as a rock to withstand the ceiling collapse with hardly a scratch.

Common Names:

Name	Pronounced	Usage
Asun	AH-soon	Spanish
Sonja	ZAWN-yah (German), SON-yah (Finnish)	German, Dutch, Swedish, Norwegian, Danish, Icelandic, Finnish, Slovene, Serbian, Croatian, Macedonia
Eglantine	EG-lən-teen	English (Rare)
Shahd	-	Arabic
Svea	SVE-ah	Swedish
Minoru	mee-no-ṙoo	Japanese