I. ˈthərd adjective
Etymology: Middle English thridde, thirde, from Old English thridda, thirdda; akin to Latin tertius third, Greek tritos, treis three — more at three
Date: before 12th century
1.
a. : being next after the second in place or time
the third taxi in line
b. : ranking next after the second of a grade or degree in authority or precedence
served as third mate
c. : being the forward speed or gear next higher than second especially in a motor vehicle
2.
a. : being one of three equal parts into which something is divisible
a third share of the money
b. : being the last in each group of three in a series
take out every third card
• third or third·ly adverb
II. noun
Date: 14th century
1. : one of three equal parts of something
a third of the pie
2.
a. — see number table
b. : one that is next after second in rank, position, authority, or precedence
the third in line
3.
a. : the musical interval embracing three diatonic degrees
b. : a tone at this interval ; specifically : mediant
c. : the harmonic combination of two tones a third apart
4. plural : merchandise whose quality falls below the manufacturer's standard for seconds
5. : third base
6. : the third forward gear or speed especially of a motor vehicle