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. ceruleum), 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.
© Webster 1913.