(slang) To discreetly monitor in a creepy way. To stalk.

simple past tense and past participle of creep out

(informal) Experiencing a creepy sensation; having been weirded out.

The tendency of a design project or product cycle to accumulate more and more features or details, rather than to be completed and released at a more basic level.

(computing) The tendency of programmers to disproportionately emphasize elegance in software at the expense of other requirements such as functionality, shipping schedule, and usability.

(taxation) The move towards increased taxation when an inflation adjustment to a wage or salary pushes a taxpayer into a higher tax bracket (or, in a progressive taxation regime, further into a bracket).

(project management) Uncontrolled growth in the scope or requirements of a project.

A small but significant tendency for spring to start earlier and for autumn to end later; the result of global warming.

The inexorable tendency for the commercial aspects of Christmas to appear earlier every year.

(informal, transitive) To make uncomfortable or afraid; to give someone the creeps.