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Webster 1913 Edition

Noun.

A laggard.

Adj.

A loiterer; an idler; one who moves slowly and falls behind.

See also: lägger

lagger ‎(plural laggers)

One who installs lagging.
- 2001, Geoffrey Tweedale, Philip Hansen, Magic Mineral to Killer Dust: Turner & Newall and the Asbestos Hazard
  In particular, Turner & Newall doggedly contested any claims from the largest high-risk group outside the scheduled factory areas — the laggers.
(video games, informal) A player who lags (has a poor or slow network connection).

one who installs lagging

Blend of legal +‎ nagger

lagger ‎(plural laggers)

(slang) A member of support staff responsible for contacting lawyers to check how a case is progressing.