(idiomatic) An initiating cause of a chain of events which leads to an outcome or effect of interest.

(transitive) The action of identifying the cause of a chain of events which leads to an outcome or effect of interest. To root cause something's root cause does not necessarily imply the use of root cause analysis (RCA).

Obsolete spelling of roof

(informal) Clipping of recreation room.

simple past tense and past participle of room

(Canada, US) A room where alcoholic drinks are served over a counter.

A small room adjoining a domestic bedroom where people may dress or undress in privacy. / A room in a theatre or other performance venue in which performers may change costumes and apply makeup.

Of a plant, that has become too large and heavy to support itself, and has fallen over, so uprooting itself.

To remove or abolish completely. / To search for and discover.

(simile) Extremely nervous.