mark (v.)youdaoicibaDictYouDict[mark 词源字典]
"to put a mark on," Old English mearcian (West Saxon), merciga (Anglian) "to trace out boundaries," from Proto-Germanic *markojan (cognates: Old Norse merkja, Old Saxon markon, Old Frisian merkia, Old High German marchon, German merken "to mark, note," Middle Dutch and Dutch merken), from the root of mark (n.1).

Influenced by Scandinavian cognates. Meaning "to have a mark" is from c. 1400; that of "to notice, observe" is late 14c. Meaning "to put a numerical price on an object for sale" led to verbal phrase mark down (1859). Mark time (1833) is from military drill. Related: Marked; marking. Old French merchier "to mark, note, stamp, brand" is a Germanic loan-word.[mark etymology, mark origin, 英语词源]
mark-down (n.)youdaoicibaDictYouDict
1880, from expression mark down "reduce in price" (see mark (v.)).