To pass gradually from a sound, prosperous, or perfect state, to one of imperfection, adversity, or dissolution; to waste away; to decline; to fail; to become weak, corrupt, or disintegrated; to rot; to perish; as, a tree decays; fortunes decay; hopes decay.
- Biology To break down into component parts; rot.
- Physics To disintegrate or diminish by radioactive decay.
- Electronics To decrease gradually in magnitude. Used of voltage or current.
- Aerospace To decrease in orbit. Used of an artificial satellite.
- To fall into ruin: a civilization that had begun to decay.
- Pathology To decline in health or vigor; waste away.
- To decline from a state of normality, excellence, or prosperity; deteriorate.
- To cause to decay.
- The destruction or decomposition of organic matter as a result of bacterial or fungal action; rot.
- Rotted matter.
- Physics Radioactive decay.
- Aerospace The decrease in orbital altitude of an artificial satellite as a result of conditions such as atmospheric drag.
- A gradual deterioration to an inferior state: tooth decay; urban decay.
- A falling into ruin.