/jerrk"waw'teuhr, -wot'euhr/ , adj.
1. Informal. insignificant and out-of-the-way: a jerkwater town.
2. (formerly) off the main line: a jerkwater train.
n.
3. (formerly) a train not running on the main line.
[ 1875-80, Amer.; JERK 1 + WATER; so called from the jerking (i.e., drawing) of water to fill buckets for supplying a steam locomotive ]