1. Jewelry consisting of a circlet of precious metal, often set with jewels, worn on the finger: Mildred was wearing rings on every finger of both hands.
2. Something which is shaped like a circle: The smoker was blowing smoke rings into the air.

Patricia put her keys on a new key ring.

3. An area which is used for putting on shows and may be surrounded by ropes or some other outer restrictions: Examples of show rings include: a circus ring, a rodeo ring, a boxing ring, a wrestling ring, etc.
4. A group of people who are involved in some kind of illegal or dishonest activities: The police broke up two drug rings and a Mexican smuggling ring last week.

1. To cause a device or an object; such as, a bell to make sounds: The hotel clerk rang a bell at the desk to get the attention of someone to carry the customer's baggage to the room.

When Jillian went to visit her friends, she rang the door bell so they would let her in.

2. To make a sound as a signal of an event or a specific time: The church bells rang early on Sunday to summon people to the religious service.
3. To fill a place or an area with sound: The cheers were ringing through the gym as the school team won the championship.
4. To appear to have a particular quality or character: Jim's excuse for getting home late didn't ring true with his parents.
5. To form a circle around or to surround something or a person: Small cottages are ringing the lake.

The ring of hot gas and dust that encircles a black hole, formed from material torn off the companion star to the black hole.

In losing its initial angular momentum, the hot material descends into the black hole, friction causing it to reach temperatures high enough to produce x-rays.

It is by the accretion ring emission that makes it possible for the presence of the black hole to be inferred.

Saturn's inner ring, also known as the C-ring, which extends inward to the planet from the brightest ring or the B-ring.

1. A phenomenon seen as a flash of sunlight shines down a lunar valley during a total solar eclipse.
2. An effect created as the total phase of a solar eclipse is about to begin, when the last Baily's bead, a remaining bit of phosphere, glows so intensely by contrast with the sun's faint corona that it looks like the jewel on a ring.

It also refers to the equivalent phase at the end of totality.