Gravity

n. attractive force which causes all bodies to move toward the center of the earth; weight, heaviness; severity; seriousness; solemnity

Gravitation is a natural phenomenon by which all objects with mass attract each other. In everyday life, gravitation is most familiar as the agency that endows objects with weight. It is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth, for the formation of tides; for convection (by which hot fluids rise); for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe. Gravitation is also the reason for the very existence of the Earth, the Sun, and most macroscopic objects in the universe; without it, matter would not have coalesced into these large masses and life, as we know it, would not exist.
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Gravity /grav·i·ty/ 1. the phenomenon by which two bodies having mass are attracted to each other. 2. [more]Gravity - Community and Resources

Noun
1. (physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; "the more remote the body the less the gravity"; "the gravitation between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them"; "gravitation cannot be held responsible for people falling in love"--Albert Einstein
(synonym) gravitation, gravitational attraction, gravitational force
(hypernym) attraction, attractive force
(hyponym) solar gravity
(derivation) gravitate
(classification) physics, physical science, natural philosophy
2. a manner that is serious and solemn
(synonym) graveness, sobriety, soberness, somberness
(hypernym) seriousness, earnestness, serious-mindedness, sincerity
(hyponym) stodginess, stuffiness
3. a solemn and dignified feeling
(synonym) solemnity
(antonym) levity
(hypernym) feeling
(hyponym) earnestness, seriousness, sincerity

(a.)
The tendency of a mass of matter toward a center of attraction; esp., the tendency of a body toward the center of the earth; terrestrial gravitation.
  

(a.)
The state of having weight; beaviness; as, the gravity of lead.
  

(a.)
Sobriety of character or demeanor.
  

(a.)
Lowness of tone; -- opposed to acuteness.
  

(a.)
Importance, significance, dignity, etc; hence, seriousness; enormity; as, the gravity of an offense.