Of flowers, having more than the normal number of petals.

entertainmentlifestylemusicOf an instrument, sounding an octave lower.

• a double bass

entertainmentlifestylemusicOf time, twice as fast.

bridgegamesA call that increases certain scoring points if the last preceding bid becomes the contract.

ball-gamesbilliardsgamesA strike in which the object ball is struck so as to make it rebound against the cushion to an opposite pocket.

• Brecel fired in doubles, a succession of stunning long pots and seemingly cleared balls at will as he rattled through the first four frames in under an hour.

A bet on two horses in different races in which any winnings from the first race are placed on the horse in the later race.

• Not only did I collect on the double; I had the win and the place money as well.

dartsgamesThe narrow outermost ring on a dartboard.

dartsgamesA hit on this ring.

dominoesgamesA tile that has the same value (i.e., the same number of pips) on both sides.

computingengineeringmathematicsA double-precision floating-point number.

• The sine function returns a double.

ball-gamesgameshobbiesTwo competitions, usually one league and one cup, won by the same team in a single season.

hobbieslifestylerowingA boat for two scullers.

hobbieslifestylesportsThe feat of scoring twice in one game.

• DJ Campbell grabbed a second-half double as Blackpool made Sunderland pay for a host of missed chances to secure a fifth away league win of the season.

hobbieslifestylesportsThe feat of winning two events in a single meet or competition.

• In 1996, Michael Johnson achieved a double by winning both the 200 and 400 meter dashes.

ball-gamescricketgamesThe achievement of 1000 runs and 100 wickets taken in a single season.

historicalA former French coin worth one-sixth of a sou.

historicalA copper coin worth one-eighth of a penny.

• As for doubles, they are not worth anything now; and I have still got an egg-cupful my mother used to keep handy to give the baker change from a farthing.

entertainmentlifestylemusicPlaying the same part on two instruments, alternately.

ChristianityA double feast.

Synonym of double-quick (“fast marching pace”).

entertainmentlifestylemusicA secondary instrument with which a musician is skilled.

• The saxophone is a valuable and rewarding double, and opens up many gigs that aren’t available to players of just the “orchestral” woodwinds.

datedslangA double-cross or betrayal.

• His fellows had chaffed him much upon the way that astute adventurer had bamboozled him, or, in their vernacular, "put the double on him," and vowed that all his energies should be devoted to a return match.

A double agent.

• 'This is 007 speaking. This is an open line. It's an emergency. Can you hear me? Pass this on at once. 3030 was a double, working for Redland.

slangSomeone who identifies with the same kintype.

• seeing a double of their kintype can feel threatening or disorienting, or just make them kind of uncomfortable if their kintype is very personal to them.

slangSomeone who yumeships with the same character as another person.

• Haven’t been in the yumeshipping space for all that long so I never really knew if I was sharing or not until I talked to a double.

To serve a second role or have a second purpose.

• A spork is a kind of fork that doubles as a spoon.

To act as substitute for (another theatrical performer in a certain role, etc).

• Laforêt, who (as the French express it), doubles Lainez, that is, performs the same characters in his absence.
• […] and when she attempted to double the part of her mother, she equally failed in playing the great or agreeable lady.

entertainmentlifestyletheaterTo play (both one part and another, in the same play, etc).

• When, therefore, Briggs, the sedate, middle-aged individual, who in the Markham household doubles the roles of butler and valet, makes his appearance, his master affects to be in a great hurry, looks at his watch, and says : […]
• Miss Theby doubles in the part of Rose and the native girl in the Philippines. This is a problem plot in which a young man leaves the girl of his choice because she has had an affair in her earlier years. He goes to the Philippines, […]

To turn sharply, following a winding course.

nauticaltransportTo sail around (a headland or other point).

• Sailing along the coast, he doubled the promontory of Carthage.
• […] though the Iſland itſelf was not very large […] I found a great Ledge of Rocks lie out about two Leagues into the Sea[…]ſo that I was oblig’d to go a great Way out to Sea to double the Point.

entertainmentlifestylemusicTo duplicate (a part) either in unison or at the octave above or below it.

entertainmentlifestylemusicTo be capable of performing (upon an additional instrument).

bridgegamesTo make a call that will double certain scoring points if the preceding bid becomes the contract.

card-gamesgamesTo double down.

ball-gamesbilliardsgamesTo cause (a ball) to rebound from a cushion before entering the pocket.

To go or march at twice the normal speed.

• "You double down to the harbour, my lad," said the Captain to Strickland, "and sign on. You've got your papers." Strickland set off at once, and that was the last Captain Nichols saw of him.

To multiply the strength or effect of by two.

• Sorry, this store does not double coupons.

governmentmilitarypoliticsTo unite, as ranks or files, so as to form one from each two.

informalbroadcastingmediaradioTo transmit simultaneously on the same channel as another station, either unintentionally or deliberately, causing interference.

• Could you please repeat your last transmission? Another station was doubling with you.

espionagegovernmentmilitaryTo operate as a double agent.

• Was this simply the cover name of an Allied spy-code named the Brass Monkey? […] The possibility that the Brass Monkey himself was "doubling" (with headquarters' approval, of course) is too logical […]