Definition

/ˈsɪŋɡəl/

noun

A 45 RPM vinyl record with one song on side A and one on side B.
A popular song released and sold (on any format) nominally on its own though usually having at least one extra track.
“The Offspring released four singles from their most recent album.”
One who is not married or does not have a romantic partner.
“He went to the party, hoping to meet some friendly singles there.”
A score of one run.
A hit in baseball where the batter advances to first base.

verb

To identify or select one member of a group from the others; generally used with out, either to single out or to single (something) out.
“Eddie singled out his favorite marble from the bag.”
To get a hit that advances the batter exactly one base.
“Pedro singled in the bottom of the eighth inning, which, if converted to a run, would put the team back into contention.”
To thin out.
(of a horse) To take the irregular gait called singlefoot.
To sequester; to withdraw; to retire.

adjective

Not accompanied by anything else; one in number.
“Can you give me a single reason not to leave right now?”
Not divided in parts.
“The potatoes left the spoon and landed in a single big lump on the plate.”
Designed for the use of only one.
“a single room”
Performed by one person, or one on each side.
“a single combat”
Not married or (in modern times) not involved in a romantic relationship without being married or not dating anyone exclusively.
“Forms often ask if a person is single, married, divorced or widowed. In this context, a person who is dating someone but who has never married puts "single".”