group
1 [countable] set (of something) a group of similar things that belong together in some waya set of six chairsa complete set of her novelsa set of false teetha new set of rules to learnYou can borrow my keys—I have a spare set. see also tea set2 [countable] a group of objects used together, for example for playing a gamea chess set3 [countable + singular or plural verb] (sometimes disapproving) a group of people who have similar interests and spend a lot of time together sociallythe smart set (= rich, fashionable people)Dublin's literary set see also the jet set
TV/radio
4 [countable] a piece of equipment for receiving television or radio signals
for play/movie
5 [countable] the scenery used for a play, film/movie, etcWe need volunteers to help build and paint the set.6 [countable, uncountable] a place where a play is performed or part of a film/movie is filmedThe cast must all be on (the) set by 7 in the morning.
in sport
7 [countable] one section of a match in games such as tennis or volleyballShe won in straight sets (= without losing a set).
mathematics
8 [countable] a group of things that have a shared qualityset theory
pop music
9 [countable] a series of songs or pieces of music that a musician or group performs at a concerta stunning solo set of ten songs
class
10 [countable] (British English) a group of school students with a similar ability in a particular subjectShe's in the top set for French.
of face/body
11 [singular] set of something the way in which somebody's face or body is fixed in a particular expression, especially one showing determinationShe admired the firm set of his jaw.
hair
12 [singular] an act of arranging hair in a particular style while it is wetA shampoo and set costs £15.
becoming firm
13 [singular] the state of becoming firm or solidTo be sure of a good set when making the jam, use preserving sugar with added pectin. animal's home
14 [countable] = sett
plant
15 [countable] a young plant, shoot etc. for plantingonion sets
set 
set 