eighteen

As an adjective also

is bottom, lower.

As a numeral eighteen is

the cardinal number occurring after seventeen and before nineteen, represented in roman numerals as xviii and in arabic numerals as 18.

As a numeral eighteen

is the cardinal number occurring after seventeen and before nineteen, represented in roman numerals as xviii and in arabic numerals as 18.

As an adjective twentieth is

the ordinal form of the number twenty.

As a noun twentieth is

a person or thing in the twentieth position.

is likely misspelled.

has no English definition.

As a numeral eighteen

is the cardinal number occurring after seventeen and before nineteen, represented in Roman numerals as XVIII and in Arabic numerals as 18.

As numerals the difference between eighteen and eight

is that eighteen is the cardinal number occurring after seventeen and before nineteen, represented in roman numerals as xviii and in arabic numerals as 18 while eight is (cardinal) a numerical value equal to ; the number occurring after seven and before nine.

As a noun eight is

the digit/figure 8 or eight can be an island in a river; an ait.

As a noun taxonomy

is the science or the technique used to make a classification.

As a numeral eighteen is

the cardinal number occurring after seventeen and before nineteen, represented in roman numerals as xviii and in arabic numerals as 18.

As a numeral eighteen

is the cardinal number occurring after seventeen and before nineteen, represented in Roman numerals as XVIII and in Arabic numerals as 18.

As an adjective eighteenish is

of about eighteen years of age.

As a numeral eighteen

is the cardinal number occurring after seventeen and before nineteen, represented in roman numerals as xviii and in arabic numerals as 18.

As a noun eighteenpence is

the monetary amount of eighteen pence.