The Collaborative International Dictionary of English v.0.48:

Tubal \Tub"al\, a.
   Of or pertaining to a tube; specifically, of or pertaining to
   one of the Fallopian tubes; as, tubal pregnancy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tubal
    adj 1: of or relating to occurring in a tube such as e.g. the
           Fallopian tube or Eustachian tube; "tubal ligation";
           "tubal pregnancy"

Easton's 1897 Bible Dictionary:

Tubal
   (1.) The fifth son of Japheth (Gen. 10:2).

     (2.) A nation, probably descended from the son of Japheth. It
   is mentioned by Isaiah (66:19), along with Javan, and by Ezekiel
   (27:13), along with Meshech, among the traders with Tyre, also
   among the confederates of Gog (Ezek. 38:2, 3; 39:1), and with
   Meshech among the nations which were to be destroyed (32:26).
   This nation was probably the Tiberini of the Greek historian
   Herodotus, a people of the Asiatic highland west of the Upper
   Euphrates, the southern range of the Caucasus, on the east of
   the Black Sea.


Hitchcock's Bible Names Dictionary (late 1800's):

Tubal, the earth; the world; confusion