Real Dictionary

lag in American English 1
a falling behind or being retarded in motion, development, etc.
to fall, move, or stay behind; loiter; linger
intransitive verb: to fail to maintain a desired pace or to keep up; fall or stay behind
noun: a lagging or falling behind; retardation
transitive verb: to fail to keep up with

lag in American English 2
a strip of insulating material used for covering boilers, cylinders, etc.
to cover with insulating material
noun: a convict or ex-convict
transitive verb: to send to penal servitude; imprison

lag in American English 3
a convict or ex-convict
to imprison
noun: one of the staves or strips that form the periphery of a wooden drum, the casing of a steam cylinder, or the like
transitive verb: to line or cover (an excavation) with lagging

lag in British English 1
noun: the act or state of slowing down or falling behind
verb: to hang (back) or fall (behind) in movement, progress, development, etc

lag in British English 2
noun: a convict or ex-convict (esp in the phrase old lag)
verb: to arrest or put in prison

lag in British English 3
noun: the insulating casing of a steam cylinder, boiler, etc; lagging
verb: to cover (a pipe, cylinder, etc) with lagging to prevent loss of heat

lag in Electrical Engineering
noun: Lag is the delay between voltage signal and the corresponding current signal.