tense
     adj 1: in or of a state of physical or nervous tension [ant: {relaxed}]
     2: pronounced with relatively tense tongue muscles (e.g., the
        vowel sound in `beat') [ant: {lax}]
     3: taut or rigid; stretched tight; "tense piano strings" [ant:
        {lax}]
     n : a grammatical category of verbs used to express distinctions
         of time
     v 1: stretch or force to the limit; "strain the rope" [syn: {strain}]
     2: increase the tension on; "tense a rope"
     3: become tense or tenser; "He tensed up when he saw his
        opponent enter the room" [syn: {tense up}] [ant: {relax}]
     4: make tense and uneasy or nervous or anxious; [syn: {strain},
         {tense up}] [ant: {relax}, {relax}]
Source: WordNet® 2.0

tense adj. Of programs, very clever and efficient. A tense piece of
   code often got that way because it was highly {bum}med, but sometimes it
   was just based on a great idea. A comment in a clever routine by Mike
   Kazar, once a grad-student hacker at CMU: "This routine is so tense it
   will bring tears to your eyes." A tense programmer is one who produces
   tense code.


Source: The Jargon File