Adjective

1. Mean; dirty; contemptible; scrubby.

   "How solitary, how scrub, does this town look!" -Walpole.

   "No little scrub joint shall come on my board." -Swift.

Noun

1. One who labors hard and lives meanly; a mean fellow.

   We should go there in as proper a manner possible; nor altogether like the scrubs about us.

2. One who is a freak or unable to complete easy tasks.

   You are such a scrub! Instead of washing the dishes you put the used food on your face!

3. A thicket or jungle, often specified by the name of the prevailing plant; as, oak scrub, palmetto scrub, etc.
4. One of the common livestock of a region of no particular breed or not of pure breed, esp. when inferior in size, etc. Often used to refer to male animals unsuited for breeding.
5. Vegetation of inferior quality, though sometimes thick and impenetrable, growing in poor soil or in sand; also, brush.
6. One who is no longer new to a game but still exhibits novice tendencies.

   "What a scrub."

7. One not on the first team of players, a substitute.

Verb

1. To rub hard; to wash with rubbing; usually, to rub with a wet brush, or with something coarse or rough, for the purpose of cleaning or brightening; as, to scrub a floor, a doorplate.
2. To rub anything hard, especially with a wet brush; to scour;
3. To be diligent and penurious; as, to scrub hard for a living.
4. To call off a scheduled event; to cancel.

   Engineers had to scrub the satellite launch due to bad weather.

Noun

1. An instance of scrubbing.
2. A cancellation.
3. A worn-out brush.
4. One who scrubs.
5. Clothing worn while performing surgery.