ShakespearesWords.com

jar / jars, at

Old form(s): iarre, iarres

in / into conflict, in / into a state of dissension

2H6 I.i.251	[York alone] Watch [till] ... Humphrey with the peers be fallen at jars
2H6 IV.viii.40	[Clifford to the rebels] whilst you live at jar, / The fearful French ... / Should make a start o'er seas and vanquish you?