logical
     adj 1: capable of or reflecting the capability for correct and
            valid reasoning; "a logical mind" [ant: {illogical}]
     2: in accordance with reason or logic; "a logical conclusion"
        [syn: {legitimate}]
     3: marked by an orderly, logical, and aesthetically consistent
        relation of parts; "a logical argument"; "the orderly
        presentation" [syn: {consistent}, {ordered}, {orderly}]
     4: based on known statements or events or conditions; "rain was
        a logical expectation, given the time of year"
     5: capable of thinking and expressing yourself in a clear and
        consistent manner; "a lucid thinker"; "she was more
        coherent than she had been just after the accident" [syn:
        {coherent}, {lucid}]
Source: WordNet® 2.0

logical adj. [from the technical term `logical device', wherein a
   physical device is referred to by an arbitrary `logical' name] Having
   the role of. If a person (say, Les Earnest at SAIL) who had long held a
   certain post left and were replaced, the replacement would for a while
   be known as the `logical' Les Earnest. (This does not imply any judgment
   on the replacement.) Compare {virtual}.

   At Stanford, `logical' compass directions denote a coordinate system
   relative to El Camino Real, in which `logical north' is always toward
   San Francisco and `logical south' is always toward San Jose-in spite of
   the fact that El Camino Real runs physical north/south near San
   Francisco, physical east/west near San Jose, and along a curve
   everywhere in between. (The best rule of thumb here is that, by
   definition, El Camino Real always runs logical north-south.)

   In giving directions, one might say: "To get to Rincon Tarasco
   restaurant, get onto {El Camino Bignum} going logical north." Using the
   word `logical' helps to prevent the recipient from worrying about that
   the fact that the sun is setting almost directly in front of him. The
   concept is reinforced by North American highways which are almost, but
   not quite, consistently labeled with logical rather than physical
   directions. A similar situation exists at MIT: Route 128 (famous for the
   electronics industry that grew up along it) wraps roughly 3 quarters
   around Boston at a radius of 10 miles, terminating near the coastline at
   each end. It would be most precise to describe the two directions along
   this highway as `clockwise' and `counterclockwise', but the road signs
   all say "north" and "south", respectively. A hacker might describe these
   directions as `logical north' and `logical south', to indicate that they
   are conventional directions not corresponding to the usual denotation
   for those words.


Source: The Jargon File