(before adjective) very, all too. / (before adverb) to a high degree; very well or very much

(chess) The only move to maintain the current evaluation of the position. / Used other than figuratively or idiomatically: see only, move.

(computing) A computer memory chip that stores values but does not allow updates, in which the values are nonvolatile in that they are retained even when the computer is unpowered.

The situation where an event is so well attended, or public transportation so full, that all of the seats in the venue are occupied, leaving only the ground or the floor for other people.

A market at which vendors may only sell items which they or their employees produce.

Alternative spelling of read-only memory

(idiomatic) Alternative form of time will tell

(computing) A permission to access files or directories where the user is only allowed to read or view, not to make changes.

Alternative form of God knows (“it is unknown to people”)

(idiomatic, almost always preceded by the) The only opportunity, activity, or resource available.