From Longman Dictionary of Contemporary Englishmark somebody/something ↔ off phrasal verb1 SEPARATEto make an area separate by drawing a line around it, putting a rope around it etc The competitors’ arena had been marked off with cones.2 FINISH DOING somethingto make a mark on a list to show that something has been done or completed SYN tick off, check off Mark off each of the names on the list as I call them out.3 DIFFERENT British English to make something or someone different from other things or people of a similar type SYN distinguish from Sara’s natural flair for languages marked her off from the other students. → mark→ See Verb table
Examples from the Corpus
mark off• Dollar: 104. 93 yen, up 0. 40; 1. 4360 marks, off 0. 0030.• Dollar: 105. 25 yen, up 0. 38; 1. 4425 marks, off 0. 0035.• Dollar: 105. 32 yen, up 0. 07; 1. 4390 marks, off 0. 0035.• Firstly, you will need to make a card template for your scallops in order to mark them off accurately.• He advocates marking the stretchers off one at a time instead of squaring cross all four at once.• D., said that it was on the Grand River on a marked road off U. S. Highway 12.• White lines marking the area off were painted Thursday.• It marked us off, you might say - from the literary crowd, I mean. 