Candle

a long, usually slender piece of tallow or wax with an embedded wick that is burned to give light.
something resembling a candle in appearance or use.
Optics.

(formerly) candela.
Also called international candle. a unit of luminous intensity, defined as a fraction of the luminous intensity of a group of 45 carbon-filament lamps: used from 1909 to 1948 as the international standard.
a unit of luminous intensity, equal to the luminous intensity of a wax candle of standard specifications: used prior to 1909 as the international standard.
Abbreviation: c., c.

to examine (eggs) for freshness, fertility, etc., by holding them up to a bright light.
to hold (a bottle of wine) in front of a lighted candle while decanting so as to detect sediment and prevent its being poured off with the wine.
burn the / one’s candle at both ends. burn1 (def 54).
hold a candle to, to compare favorably with (usually used in the negative):
She’s smart, but she can’t hold a candle to her sister.
worth the candle, worth the trouble or effort involved (usually used in the negative):
Trying to win them over to your viewpoint is not worth the candle.
Contemporary Examples

As 2014 Began, a Fateful Path to a Catholic Priest’s Murder Michael Daly January 2, 2014
Settlement Construction Hearing Paused For Obama Visit Orly Halpern March 13, 2013
Does Jeffrey MacDonald Belong in Jail? Megan McArdle January 2, 2013
How ‘Transcendence’ Director Wally Pfister Became Christopher Nolan’s Secret Weapon Andrew Romano April 16, 2014
Woody Allen’s Opening Night at Cannes Richard Porton May 11, 2011

Historical Examples

Alonzo and Melissa Daniel Jackson, Jr.
Left Behind James Otis
Poor Folk in Spain Jan Gordon
Harry’s Ladder to Learning Anonymous
The Complete Opera Book Gustav Kobb

noun
a cylindrical piece of wax, tallow, or other fatty substance surrounding a wick, which is burned to produce light
(physics)

See international candle
another name for candela

burn the candle at both ends, to exhaust oneself, esp by being up late and getting up early to work
(informal) not hold a candle to, to be inferior or contemptible in comparison with: your dog doesn’t hold a candle to mine
(informal) not worth the candle, not worth the price or trouble entailed (esp in the phrase the game’s not worth the candle)
verb
(transitive) to examine (eggs) for freshness or the likelihood of being hatched by viewing them against a bright light
n.

see:

burn the candle at both ends
game is not worth the candle
hold a candle to