sextillion

As an adjective undefined is

lacking a definition or value.

As numerals the difference between sextillion and quadrillion

is that sextillion is (US; modern British & Australian, short scale) A trillion billion: 1 followed by 21 zeros, 10²¹ while quadrillion is a thousand trillion: 1 followed by fifteen zeros, 10¹⁵.

As a noun quadrillion is

any very large number, exceeding normal description.

As a numeral decillion

is (us; modern british & australian, ) 10³³.

As a noun zillion

is an unspecified large number (of).

As a numeral sextillion is

(US; modern British & Australian, short scale) A trillion billion: 1 followed by 21 zeros, 10²¹.

is likely misspelled.

has no English definition.

As a numeral sextillion

is (US; modern British & Australian, short scale) A trillion billion: 1 followed by 21 zeros, 10²¹.

As an adjective sextillionfold is

(rare) by a multiple of one sextillion; by a sextillion times as much or as many.

As an adverb sextillionfold is

(rare) by a factor of one sextillion.

As a numeral sextillion

is (US; modern British & Australian, short scale) A trillion billion: 1 followed by 21 zeros, 10²¹.

As a noun zettaton is

a measure of the strength of an explosion or a bomb based on how many sextillion tons of TNT would be needed to produce the same energy.