position six in a countable series of things
"She finished in sixth place during the marathon race."
the musical interval between one note and another six notes away from it
"The composer chose a sixth to create a wide, resonant sound in that particular chord progression."
The person or thing in the sixth position.
"She finished as the sixth runner across the finish line."
In plain English: A sixth is another way to write 1/6, which means you have divided something into six equal parts and are talking about just one of them.
"She won six times in her career, making this victory just another sixth on the list."
to divide by six, which also means multiplying a denominator by six
"The sixth of twenty-four is four, just as dividing the fraction three over two by six results in three over twelve."
In plain English: To sixth someone means to give them an official order to stop moving and stay exactly where they are until told otherwise by their superior officer.
"The sixth place in line was where I stood to buy my ticket."
The ordinal form of the number six.
"She finished sixth in the race, crossing the line just behind fifth place."
In plain English: Sixth is an adjective used to describe something that comes after fifth and before seventh in order, rank, or time.
"She was born on our sixth birthday party."
Usage: Use "sixth" as an adjective before a noun to indicate rank order, such as "the sixth chapter," rather than using it after the article and noun like "the chapter sixth." Do not confuse this ordinal indicator with the fraction one-sixth when describing parts of a whole.
The word sixth comes from the Old English siexta and the Proto-Germanic root *sehstô. It originally meant "sixth" in the same way that modern English uses the ordinal suffix -th added to the number six.