1. Having relatively great weight: a heavy load.
2. Having relatively high density; having a high specific gravity.
3. a. Large, as in number or quantity: a heavy turnout; heavy casualties. b. Large in yield or output: heavy rainfall.
4. Of great intensity: heavy activity; heavy fighting.
5. a. Having great power or force: a heavy punch. b. Violent; rough: heavy seas.
6. a. Equipped with massive armaments and weapons: a heavy cruiser; heavy infantry. b. Large enough to fire powerful shells: heavy guns.
7. a. Indulging to a great degree: a heavy drinker. b. Involved or participating on a large scale: a heavy investor.
8. Of great import or seriousness; grave: heavy matters of state.
9. a. Having considerable thickness: a heavy coat. b. Broad or coarse: drew the face with heavy lines.
10. a. Dense; thick: a heavy fog. b. Slow to dissipate; strong: "There was a heavy fragrance of flowers and lemon trees" (Mario Puzo). c. Too dense or rich to digest easily: a heavy dessert. d. Insufficiently leavened: heavy bread. e. Full of clay and readily saturated: heavy soil.
11. a. Weighed down; burdened: trees heavy with plums. b. Emotionally weighed down; despondent: a heavy heart. c. Marked by or exhibiting weariness: heavy lids. d. Sad or painful: heavy news.
12. a. Hard to do or accomplish; arduous: heavy going; heavy reading. b. Not easily borne; oppressive: heavy taxes.
13. Lacking vitality; deficient in vivacity or grace: a heavy gait; heavy humor.
14. Sharply inclined; steep: a heavy grade.
15. Having a large capacity or designed for rough work: a heavy truck.
16. Of, relating to, or involving the large-scale production of basic products, such as steel: heavy industry.
17. Of or relating to a serious dramatic role.
18. Physics. Of or relating to an isotope with an atomic mass greater than the average mass of that element.
19. Loud; sonorous: a heavy sound; heavy breathing.
20. Linguistics. Of, relating to, or being a syllable ending in a long vowel or in a vowel plus two consonants.
21. Slang. a. Of great significance or profundity. b. Very popular or important: a rock star who is really heavy.
Synonyms: heavy, weighty, hefty, massive, ponderous, cumbersome. These adjectives mean having a relatively great weight. Heavy refers to what has great weight (a heavy boulder; a heavy load); figuratively it applies to what is burdensome or oppressive to the spirit (heavy responsibilities; heavy losses). Weighty literally denotes having considerable weight (a weighty package); figuratively it describes what is onerous, serious, or important (the weighty cares of a head of state; a weighty problem; a weighty decision). Hefty refers principally to physical heaviness or brawniness: a hefty dictionary; a tall, hefty wrestler. Massive describes what is bulky, heavy, solid, and strong: a massive head; massive marble columns; a massive gold chain. Ponderous refers to what has great mass and weight and usually implies unwieldiness: ponderous prehistoric beasts. Figuratively it describes what is complicated, involved, or lacking in grace: a book with a ponderous plot; a ponderous compliment. Something cumbersome is difficult to move, handle, or deal with because it is heavy, bulky, or clumsy: cumbersome luggage; a cumbersome writing style.