1.  ponderous(s = adj.all) heavy, lumbering - slow and laborious because of weight; "the heavy tread of tired troops"; "moved with a lumbering sag-bellied trot"; "ponderous prehistoric beasts"; "a ponderous yawn"
Derived form noun ponderousness₂

2.  ponderous(s = adj.all) - having great mass and weight and unwieldiness; "a ponderous stone"; "a ponderous burden"; "ponderous weapons"
Derived forms noun ponderosity₁, noun ponderousness₂

3.  ponderous(s = adj.all) - labored and dull; "a ponderous speech"
Derived form noun ponderousness₁

1.  Very heavy; weighty; as, a ponderous shield; a ponderous load; the ponderous elephant. [1913 Webster]
"The sepulcher . . .
Hath oped his ponderous and marble jaws." [1913 Webster]

2.  Important; momentous; forcible. Shak. [1913 Webster]

3.  Heavy; dull; wanting; lightless or spirit; as, a ponderous style; a ponderous joke. [1913 Webster]

ponderous, adj.
1 heavy; unwieldy.
2 laborious.
3 (of style etc.) dull; tedious.

Derivative:
ponderosity n. ponderously adv. ponderousness n.

Etymology:
ME f. L ponderosus f. pondus -eris weight

N  inelegance, stiffness, unlettered Muse, barbarism, slang, solecism, mannerism, euphuism, fustian, cacophony, words that break the teeth, words that dislocate the jaw, marinism, inelegant, graceless, ungraceful, harsh, abrupt, dry, stiff, cramped, formal, guinde, forced, labored, artificial, mannered, ponderous, awkward, uncourtly, unpolished, turgid, affected, euphuistic, barbarous, uncouth, grotesque, rude, crude, halting, offensive to ears polite, Spoken Language.

N  gravity, gravitation, weight, heaviness, specific gravity, pondorosity, pressure, load, burden, burthen, ballast, counterpoise, lump of, mass of, weight of, lead, millstone, mountain, Ossa on Pelion, weighing, ponderation, trutination, weights, avoirdupois weight, troy weight, apothecaries' weight, grain, scruple, drachma, ounce, pound, lb, arroba, load, stone, hundredweight, cwt, ton, long ton, metric ton, quintal, carat, pennyweight, tod, gram, centigram, milligram, microgram, kilogram, nanogram, picogram, femtogram, attogram, balance, scale, scales, steelyard, beam, weighbridge, spring balance, piezoelectric balance, analytical balance, two-pan balance, one-pan balance, postal scale, baby scale, statics, weighty, weighing, heavy as lead, ponderous, ponderable, lumpish, lumpy, cumbersome, burdensome, cumbrous, unwieldy, massive, incumbent, superincumbent.