1) Dawdler 2) Do-nothing 3) Drone 4) Idler 5) Laggard 6) Layabout 7) Loafer 8) One falling behind 9) One who falls behind 10) Slow mover 11) Someone who lags behind 12) Trailer 1) Dawdler 2) Lingerer 3) Loiterer 4) Potterer 5) Putterer 6) Slowcoach 7) Slowpoke 8) Straggler 9) Strayer 10) Trailer 
• (n.) A laggard.
Lag'ger noun A laggard.