six

Concise Oxford English Dictionary © 2008 Oxford University Press:
six/sɪks/

▶cardinal number

• 1 equivalent to the product of two and three; one more than five, or four less than ten; 6. (Roman numeral: vi or VI)

• 2 Cricket a hit that reaches the boundary without first striking the ground, scoring six runs.

• 3 a group of six Brownies or Cubs.

– phrases
at sixes and sevens in a state of confusion or disarray.
knock (or hit) someone for six Brit. informal utterly surprise or overcome someone.
six feet under informal dead and buried.
six of one and half a dozen of the other a situation in which there is little difference between two alternatives.

– derivatives
sixfold adjective & adverb.

– origin OE siex, six, syx, of Gmc origin.