Staid means settled, serious and rather dull. A staid old firm, staid and respectable, rather staid.
It is a criticism dressed as a description, since calling an institution staid says it has stopped changing. It is an old spelling of stayed, and the sense of somebody who has settled in place is exactly right.
1adjectivestaidSettled, serious and rather dull.
“Her staid old uncle wore the same grey suit every day and never told a joke.”
staid is a quality.
An old spelling of stayed, the past participle of stay, used as an adjective.
Proto-Indo-European
*steh₂-
English, today
staid
From an obsolete spelling of stayed, the past participle of stay, used as an adjective.
Etymology from Wiktionary, CC BY-SA