WordNet sense 1 (formerly the basic unit of money in Germany):

Deutschmark, Deutsche Mark, German mark

WordNet sense 2 (Apostle and companion of Saint Peter; assumed to be the author of the second Gospel):

Saint Mark, St. Mark

WordNet sense 3 (a person who is gullible and easy to take advantage of):

chump, fool, gull, mug, patsy, sucker, fall guy, soft touch

WordNet sense 4 (a distinguishing symbol):

marker, marking

WordNet sense 5 (a reference point to shoot at):

target

WordNet sense 6 (a visible indication made on a surface):

print

WordNet sense 7 (a symbol of disgrace or infamy):

brand, stain, stigma

WordNet sense 8 (a perceptible indication of something not immediately apparent (as a visible clue that something has happened)):

sign

WordNet sense 9 (the shortest of the four Gospels in the New Testament):

Gospel According to Mark

WordNet sense 10 (a number or letter indicating quality (especially of a student's performance)):

grade, score

WordNet sense 11 (an indication of damage):

scar, scrape, scratch

WordNet sense 12 (a marking that consists of lines that cross each other):

crisscross, cross

WordNet sense 13 (to accuse or condemn or openly or formally or brand as disgraceful):

denounce, stigmatize, stigmatise

WordNet sense 14 (notice or perceive):

note, notice

WordNet sense 15 (attach a tag or label to):

label, tag

WordNet sense 16 (mark with a scar):

pit, pock

WordNet sense 17 (make small marks into the surface of):

nock

WordNet sense 18 (establish as the highest level or best performance):

set

WordNet sense 19 (remove from a list):

cross off, strike out, cross out, strike off

WordNet sense 20 (put a check mark on or near or next to):

check, tick, mark off, tick off

WordNet sense 21 (be a distinctive feature, attribute, or trait; sometimes in a very positive sense):

differentiate, distinguish

WordNet sense 22 (mark by some ceremony or observation):

commemorate

WordNet sense 23 (insert punctuation marks into):

punctuate

WordNet sense 24 (something that exactly succeeds in achieving its goal):

bull's eye, bell ringer, home run