Thayer's Greek Lexicon

 1. a rod or straight piece of rounded wood to which any thing is
fastened to keep it straight
  1) used for various purposes
1a1. a measuring rod, rule
1a2. a carpenter's line or measuring tape
1a3. the measure of a leap, as in the Olympic games
2. a definitely bounded or fixed space within the limits of which one's
power of influence is confined
  1) the province assigned one
  2) one's sphere of activity
3. metaph. any rule or standard, a principle or law of investigating,
judging, living, acting