The correct spelling of the word "un cage" is actually "une cage". The "e" at the end of "une" is important because it indicates that the word is feminine. In IPA phonetic transcription, "une cage" would be represented as /yn kaʒ/. The "y" represents the French "u" sound, while the "ɑ" represents the French "a" sound. The "ʒ" represents the French "j" sound, which is similar to the English "zh" sound.
The word "uncage" is composed of the prefix "un-" which means "not" or "the opposite of", and the noun "cage", referring to a structure used to confine or enclose something. The etymology of "cage" traces back to the Latin word "cavea", meaning "hollow place" or "enclosure", which is also the origin of the English word "cave". Over time, the meaning of "cage" evolved to specifically denote a structure used for holding captive animals, and "uncage" emerged as its antonym, indicating the act of releasing something from confinement.