linger: [13] Etymologically, to linger is to remain ‘longer’ than one should. Like its relatives, German längen and Dutch lengen, it goes back to a prehistoric Germanic *langgjan ‘lengthen’. In Old Norse this became lengja, which was borrowed into English in the 10th century as leng. By now, ‘lengthen’ had progressed metaphorically via ‘prolong’ to ‘delay’, which is what it meant when linger was derived from it in the 13th century. => long
linger (v.)
c. 1300, lenger "reside, dwell," northern England frequentative of lengen "to tarry," from Old English lengan "prolong, lengthen," from Proto-Germanic *langjan "to make long" (cognates: Old Frisian lendza, Old High German lengan, Dutch lengen "to lengthen"), source of Old English lang (see long (adj.)). Sense of "delay going, depart slowly and unwillingly" is from 1520s. Related: Lingered; lingering.