clump

Short definition from Wiktionary

Noun

1. 1
   A cluster or lump; an unshaped piece or mass.
2. 2
   A thick group or bunch, especially of bushes or hair.
3. 3
   A dull thud.
4. 4
   The compressed clay of coal strata.
5. 5
   A small group of trees or plants.
6. 6
   A thick addition to the sole of a shoe.

Verb

1. 1
   To form clusters or lumps.
2. 2
   To gather in dense groups.
3. 3
   To walk with heavy footfalls.
4. 4
   To strike; to beat.