Full has 20 different meanings across 5 categories:
Noun · Verb · Adjective · Adverb · Proper Noun
the time when the Moon is fully illuminated
"the moon is at the full"
Utmost measure or extent; highest state or degree; the state, position, or moment of fullness; fill.
"The reservoir reached its full capacity just before the floodgates had to be opened."
In plain English: In this context, full is not a noun but an adjective that means completely filled or having everything you need.
"The full was complete after he ate his dinner."
Usage: Use "full" as a noun only in specific idioms like "to the full," meaning to the utmost extent or completely. In standard modern English, it is almost exclusively an adjective describing capacity or completeness rather than standing alone as a noun.
make (a garment) fuller by pleating or gathering
"The tailor gathered and stitched the excess fabric to full the skirt before hemming it."
To become full or wholly illuminated.
"The washerwoman spent all afternoon fulling the heavy woolen blankets before they were ready for sale."
To baptise.
To make cloth denser and firmer by soaking, beating and pressing, to waulk, walk
In plain English: To fill something up completely so there is no more space left inside it.
"The rain had full his pocket with coins before he noticed."
Usage: Do not use "full" as a verb in modern English; this archaic term for making cloth denser has been completely replaced by the word "to fullo" or simply "to full." Instead, use standard verbs like "fill," "press," or "pack" when you need an action that makes something full.
containing as much or as many as is possible or normal
"a full glass"
"a sky full of stars"
"a full life"
"the auditorium was full to overflowing"
Containing the maximum possible amount that can fit in the space available.
"The bus was full, so no more passengers could board."
In plain English: Full means having as much of something as you can hold or contain without any space left over.
Usage: Use full to describe a container or space that holds the maximum amount possible without overflowing, such as a full glass or a full room. Do not use it when you simply mean "complete" in an abstract sense, where complete is often more appropriate.
to the greatest degree or extent; completely or entirely; (`full' in this sense is used as a combining form)
"fully grown"
"he didn't fully understand"
"knew full well"
"full-grown"
"full-fledged"
Fully; quite; very; thoroughly; completely; exactly; entirely.
"The rain poured full down, soaking everyone who hadn't found shelter."
In plain English: When something is fully done, it has been completed all the way through with nothing left over.
"The train was full and we couldn't find a seat."
Usage: Use "fully" when you need to emphasize that an action has been completed or experienced to the greatest possible degree, such as in "I am fully aware of the risks." Avoid using "full" as an adverb because it is strictly a noun or adjective describing quantity or capacity.
A surname, from German.
"My neighbor is Mr. Full, and his family has lived in that small village for over a century."
The word "full" comes from the Old English full, which has been used with essentially the same meaning since it entered Middle English. Its roots trace back through Proto-Germanic and Proto-Indo-European to an ancient concept of being filled to capacity.