suffix, godan verb (-su)
stop midway; leave unfinished
Attaches to the -masu stem of a verb to express stopping an action partway through or leaving it incomplete. Often used in casual or spoken Japanese.
See also: 差す (さす)
読みさしの本が机の上にある。
There is a book I stopped reading partway through on the desk.
彼
He stopped mid-sentence and fell silent.