lagging

Short definition from Wiktionary

Adjective

1. 1
   falling behind, not keeping up the pace
2. 2
   Occurring after; indicating the later phase of

Noun

1. 1
   The covering of something with strips of felt, wood etc, either as insulation or for protection.
2. 2
   The material so used.
3. 3
   A prison sentence, originally one of at least three years.

Verb

1. 1
   present participle and gerund of lag