Very strong, valiant, or bold.
Very powerful, or having great command.
Very strong in numbers.
Very strong or great in corporeal power, or very able.
Violent, or very loud.
Vehement, or rushing with violence.
Very great, or vast.
Very forcible, or efficacious.
Very great or eminent in intellect or acquirements.
Great, wonderful, or performed with great power.
Very severe and distressing.
Very great, large or populous.

Important or momentous.

In a great degree. Colloquial.

In Factgirlian circles, the word mighty has powerful and implicit connotations of magnificence and glory.
Specifically, to factgirl.

Mighty

Mighty is a motion picture slang term used on set for a lighting fixture with a 2000 watt output and no focusing lens (Not to be confused with the Junior, which has a fresnel lens). Sometimes also known as a Blonde.

The Mighty is often used in a frog light set up or in other situations where the gaffer is beaming the light through diffusion and therefore does not require the focusing power of the fresnel.

The Mighty is a big brother to the 1000 watt Mickey light. On set the similar names can be told apart by remembering that Mighty Mouse can kick Mickey Mouse's ass.

Might"y (?), a. [Compar. Mightier (?); superl. Mightiest.] [AS. meahtig, mihtig; akin to G. machtig, Goth. mahteigs. See Might, n.]

1.

Possessing might; having great power or authority.

Wise in heart, and mighty in strength. Job ix. 4.

2.

Accomplished by might; hence, extraordinary; wonderful.

Matt. xi. 20.

3.

Denoting and extraordinary degree or quality in respect of size, character, importance, consequences, etc.

Mighty was their fuss about little matters. Hawthorne.

© Webster 1913.

Might"y, n.; pl. Mighties (#).

A warrior of great force and courage

1 Chron. xi. 12.

© Webster 1913.

Might"y, adv.

In a great degree; very.

Jeffrey.

We have a mighty pleasant garden. Doddridge.

© Webster 1913.