What's the meaning of state:z(zombie)?

Last known process information:

===============================

Name:          castepexe.exe

State:          Z (zombie)

Tgid:          20134

Pid:          20134

PPid:          19891

TracerPid:          0

Uid:          2003          2003          2003          2003

Gid:          2003          2003          2003          2003

Utrace:          0

FDSize:          0

Groups:          2003

Threads:          1

SigQ:          11/127330

SigPnd:          0000000000000000

ShdPnd:          0000000000000000

SigBlk:          0000000000000000

SigIgn:          0000000001000000

SigCgt:          00000001c00054ef

CapInh:          0000000000000000

CapPrm:          0000000000000000

CapEff:          0000000000000000

CapBnd:          ffffffffffffffff

Cpus_allowed:          00000002

Cpus_allowed_list:          1

Mems_allowed:          00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000003

Mems_allowed_list:          0-1

voluntary_ctxt_switches:          1651

nonvoluntary_ctxt_switches:          127451