1. A certain part or phase of an activity or process: Little Susi was 3 years old and at the stage of putting up a fuss each time her parents told her to go to bed in the evening.
2. The area where performers act or play: Grace was very nervous when she walked on to the stage to play her violin in a recital for the parents of the student soloists.
3. The production of theatrical drama in a theater: Mary thought her son was much too young to be acting regularly in plays and musicals on stage.
4. A section or part of a trip or course: The passengers on the ship entered the first stage of their trip after leaving the port in Bremerhaven.

1. To perform a drama or play: The high school students will stage or put on "My Fair Lady" the following week.
2. To present something in a misleading or deceiving way: The door-to-door salesman staged the new vacuum cleaner to make it seem to be better than all the others offered at the shops.
3. To organize an event and to take part in it: A parade was staged for the community every year at the beginning of spring.

A phase of collapes occurring in cholera, falciparum malaria, and other diseases marked by extensive intestinal discharges: The algid stage is characterized by subnormal temperature, feeble flickering pulse, hypotension, and various neurologic symptoms.

A space vehicle possessing two or more rocket units, with each successive unit firing after the stage behind it has reached burnout; at which point the latter is usually jettisoned.

The most advanced geochemical stage of diagenesis (process of chemical and physical changes in deposited sediment during its conversion to rock), characterized by the replacement of clays by micas, feldspars, and chlorites.

Diagenesis refers to changes that take place in a sediment as a result of increased temperatures and pressures, causing solid rock to form, e.g. as sand becomes sandstone.

Mica is a group of chemically and physically related aluminum silicate minerals, common in igneous and metamorphic rocks, characteristically splitting into flexible sheets used in insulation and electrical equipment.

Feldspars are any of a group of abundant rock-forming minerals occurring principally in igneous, plutonic, and some metamorphic rocks, and consisting of silicates of aluminum with potassium, sodium, calcium, and, rarely, barium. About 60 percent of the earth's outer crust is composed of feldspar.

Chlorites consist of any of a group of green soft secondary minerals consisting of the hydrated silicates of aluminium, iron, and magnesium in monoclinic crystalline form; common in metamorphic rocks.