Not a common word in Filipino conversation. It appears in literary works.
root word: sikangan, a crosspiece between posts of a house
to muzzle, choke, muffle, quiet, silence
to open someone's mouth and put a wedge between the jaws to keep them from closing shut
to place a transverse piece across or between
This famous excerpt is from Florante at Laura:
At ang balang bibig na binubukalan
ng sabing magaling at katotohanan
agad binibiyak at sinisikangan
ng kalis ng lalong dustang kamatayan.