boulder

• POS: Noun
• HYPHEN: Boul=der

CIDE DICTIONARY

boulder, n. 

 Same as Bowlder.  [1913 Webster]

boulder, n. [Cf. Sw. bullra to roar, rattle, Dan. buldre, dial. Sw. bullersteen larger kind of pebbles; perh. akin to E. bellow.].

•  A large stone, worn smooth or rounded by the action of water; a large pebble.  [1913 Webster]
•  A mass of any rock, whether rounded or not, that has been transported by natural agencies from its native bed. See Drift.  [1913 Webster]

Bowlder clay, the unstratified clay deposit of the Glacial or Drift epoch, often containing large numbers of bowlders. -- Bowlder wall, a wall constructed of large stones or bowlders.

OXFORD DICTIONARY

boulder, n. a large stone worn smooth by erosion.

Idiom

boulder-clay Geol. a mixture of boulders etc. formed by deposition from massive bodies of melting ice, to give distinctive glacial formations.

Etymology

short for boulderstone, ME f. Scand.

ROGET THESAURUS

boulder

Rotundity

N rotundity, roundness, cylindricity, sphericity, spheroidity, globosity, cylinder, cylindroid, cylindrical, barrel, drum, roll, roller, rouleau, column, rolling-pin, rundle, cone, conoid, pear shape, egg shape, bell shape, sphere, globe, ball, boulder, bowlder, spheroid, ellipsoid, oblong spheroid, oblate spheroid, prolate spheroid, drop, spherule, globule, vesicle, bulb, bullet, pellet, pelote, clew, pill, marble, pea, knob, pommel, horn, knot (convolution), curved surface, hypersphere, hyperdimensional surface, rotund, round, cylindric, cylindrical, cylindroid, columnar, lumbriciform, conic, conical, spherical, spheroidal, globular, globated, globous, globose, egg shaped, bell shaped, pear shaped, ovoid, oviform, gibbous, rixiform, campaniform, campanulate, campaniliform, fungiform, bead-like, moniliform, pyriform, bulbous, tres atque rotundus, round as an orange, round as an apple, round as a ball, round as a billiard ball, round as a cannon ball.