stare (v.)youdaoicibaDictYouDict[stare 词源字典]
Old English starian "to stare, gaze, look fixedly at," from Proto-Germanic *staren "be rigid" (cognates: Old Norse stara, Middle Low German and Middle Dutch staren, Old High German staren, German starren "to stare at;" German starren "to stiffen," starr "stiff;" Old Norse storr "proud;" Old High German storren "to stand out, project;" Gothic andstaurran "to be obstinate"), from PIE root *ster- (1) "strong, firm, stiff, rigid" (see stereo- and compare torpor).

Not originally implying rudeness. To stare (someone) down is from 1848. Related: Stared; staring.[stare etymology, stare origin, 英语词源]