The Austronesian Comparative Dictionary

*sundul touching, adjacent, as fighters presenting a united front

PWMP sundul touching, adjacent, as fighters presenting a united front

WMP
Maranao sondol adjacent, contiguous; attack
sondol-an joint, boundary
Old Javanese suṇḍul to, reaching up to, touching (from below)
Balinese ñundul be assembled close together, be arrayed (soldiers)