the basic unit of luminous intensity adopted under the Systeme International d'Unites; equal to 1/60 of the luminous intensity per square centimeter of a black body radiating at the temperature of 2,046 degrees Kelvin
"The physicist corrected her notes after realizing she had confused the obsolete candle unit with the modern candela when converting old spectral data."
A light source consisting of a wick embedded in a solid, flammable substance such as wax, tallow, or paraffin.
"She lit a candle to warm the dark room after the power went out."
In plain English: A candle is a stick of wax with a string inside that you light to make a soft glow.
"She lit a candle to set the mood for dinner."
Usage: A candle is a portable light source made of a wick surrounded by solid wax that you light to create illumination or ambiance. Use this noun when referring to the physical object itself, not the act of lighting it or the flame it produces.
examine eggs for freshness by holding them against a light
"She held each egg up to the candlelight to check if it was still fresh before adding it to the basket."
To observe the growth of an embryo inside (an egg), using a bright light source.
"The embryologist carefully candled the fertilized eggs to check if the embryos were developing properly after incubation."
In plain English: To candle something means to shine a light on it so you can see details that are hard to notice otherwise.
"She decided to candle the hidden passage by holding a flashlight against the wall."
Usage: Do not use "candle" to mean observing an embryo in an egg; that specific biological sense is archaic and rarely applies to modern conversation. Instead, reserve the verb for the common action of lighting or trimming a candle.
The word "candle" comes from the Latin candēla, which originally meant a wax object that was white or brightly shining because it came from the verb candeō ("to be white, bright"). It entered English through Middle English while retaining its core meaning of a light source.