Jacob \Ja"cob\, n. [Cf. F. Jacob. See 2d Jack.]

A Hebrew patriarch (son of Isaac, and ancestor of the Jews), who in a vision saw a ladder reaching up to heaven (--Gen. xxviii. 12); -- also called Israel.

And Jacob said . . . with my staff I passed over this Jordan, and now I am become two bands. --Gen. xxxii. 9, 10.

Thy name shall be called no more Jacob, but Israel. --Gen. xxxii. 28.

Jacob's ladder.
   (a) (Bot.) A perennial herb of the genus Polemonium (P. c[oe]ruleum), having corymbs of drooping flowers, usually blue. Gray.
   (b) (Naut.) A rope ladder, with wooden steps, for going aloft. --R. H. Dana, Jr.
   (c) (Naut.) A succession of short cracks in a defective spar.

Jacob's membrane. See Retina.

Jacob's staff.
   (a) A name given to many forms of staff or weapon, especially in the Middle Ages; a pilgrim's staff. [Obs.]

--Spenser.
   (b) (Surveying) See under Staff.

Source: Webster's Revised Unabridged Dictionary (1913)