The Collaborative International Dictionary of English v.0.48:
Jar \Jar\, v. i. [imp. & p. p. Jarred; p. pr. & vb. n.
Jarring.] [Cf. OE. charken to creak, AS. cearcian to gnash,
F. jars a gander, L. garrire to chatter, prate, OHG. kerran
to chatter, croak, G. quarren to grumble, and E. jargon,
1. To give forth a rudely quivering or tremulous sound; to
sound harshly or discordantly; as, the notes jarred on my
When such strings jar, what hope of harmony ?
A string may jar in the best master's hand.
2. To act in opposition or disagreement; to clash; to
interfere; to quarrel; to dispute.
When those renowned noble peers Greece
Through stubborn pride among themselves did jar.
For orders and degrees
Jar not with liberty, but well consist. --Milton.