adverb
(duration) For all time, for all eternity; for a lifetime; for an infinite amount of time.
(duration, colloquial, hyperbolic) For a very long time, a seeming eternity.
(frequency) Constantly or frequently.
noun
(countable, colloquial) An extremely long time.
(uncountable, colloquial or poetic) A mythical time in the future that will never come.
adjective
(chiefly informal) Permanent, lasting; constant, perpetual.