1. [n]  a cloth pad or dressing (with or without medication) applied firmly to some part of the body (to relieve discomfort or reduce fever)
2. [v]  squeeze or press together; "she compressed her lips"; "the muscle contracted"
3. [v]  make more compact by or as if by pressing; "compress the data"

1. \Com*press"\, v. t. [imp. & p. p. {Compressed}; p. pr &
   vb. n. {Compressing}.] [L. compressus, p. p. of comprimere to
   compress: com- + premere to press. See Press.]
   1. To press or squeeze together; to force into a narrower
      compass; to reduce the volume of by pressure; to compact;
      to condense; as, to compress air or water.
            Events of centuries . . . compressed within the
            compass of a single life.             --D. Webster.
            The same strength of expression, though more
            compressed, runs through his historical harangues.
                                                  --Melmoth.
   2. To embrace sexually. [Obs.] --Pope.
   Syn: To crowd; squeeze; condense; reduce; abridge.
   

2. \Com"press\, n. [F. compresse.] (Surg.)
   A folded piece of cloth, pledget of lint, etc., used to cover
   the dressing of wounds, and so placed as, by the aid of a
   bandage, to make due pressure on any part.
   

1. To feed data through any compression algorithm.

2. The Unix program "compress", now largely supplanted by gzip.

Unix compress was written in C by Joseph M. Orost, James A. Woods et al., and was widely circulated via Usenet. It uses the Lempel-Ziv Welch algorithm and normally produces files with the suffix ".Z".

Compress uses variable length codes. Initially, nine-bit codes are output until they are all used. When this occurs, ten-bit codes are used and so on, until an implementation-dependent maximum is reached.

After every 10 kilobytes of input the compression ratio is checked. If it is decreasing then the entire string table is discarded and information is collected from scratch.