Adjective

(en adjective)

Impossible to fathom or understand; incomprehensible.

The sheer numbers they attacked with were unfathomable .

* {{quote-news, year=2013, date=April 9, author=Andrei Lankov, title=Stay Cool. Call North Korea’s Bluff., work=New York Times citation

, passage=Suggestions that those leaders are irrational and their decisions unfathomable are remarkably shallow. North Korea is not a theocracy led by zealots who preach the rewards of the afterlife.}}

Difficult to penetrate.

Adjective

(complex number) (en adjective)

Made up of multiple parts; composite; not simple.

a complex''' being; a '''complex idea

* John Locke

Ideas thus made up of several simple ones put together, I call complex ; such as beauty, gratitude, a man, an army, the universe.

Not simple, easy, or straightforward; complicated.

* Whewell

When the actual motions of the heavens are calculated in the best possible way, the process is difficult and complex .

(mathematics) Of a number, of the form a + bi'', where ''a'' and ''b'' are real numbers and ''i is a square root of −1.

complex function

(geometry) A curve, polygon or other figure that crosses or intersects itself.