(computer science) a copy of a file or directory on a separate storage device; "he made a backup in case the original was accidentally damaged or erased"
an accumulation caused by clogging or a stoppage; "a traffic backup on the main street"; "he discovered a backup in the toilet"
having or showing or requiring special skill; "only the most skilled gymnasts make an Olympic team"; "a skilled surgeon has many years of training and experience"; "a skilled reconstruction of her damaged elbow"; "a skilled trade"