To be diverted; to swerve; to glance off; to divert one's eyes to another direction.
The -um- affix has more to do with uncontrolled than unintentional.
His motorcycle is swerving back and forth because he doesn't yet know how to drive it.
Often his eyes are diverted to that girl because she is beautiful.
My machete glanced off of s.t. and hit/cut my hand.
Ongoy ko wā ngaliyap pilay?
Why are you always glancing over there?