1.
To ~ an area or shape means to show where it begins and ends.
When planting seedlings I prefer to ~ the rows in advance.
PHRASAL VERB: V P n (not pron), also V n P
2.
If a particular quality or feature marks someone or something out, it makes them obviously different from other people or things.
There were several things about that evening that marked it out as very unusual...
Her independence of spirit marked her out from her male fellow officers.
PHRASAL VERB: V n P as adj/n, V n P from n, also V P n (not pron)