Orthodoxy has a number of "favorite" words - all of which fall outside the bounds of normal speech. Though we commonly use the word "mystery" (for example), popular speech never uses it in the manner of the Church. I cannot remember using the word "fullness," or even "fulfilled," in normal speech. More contemporary words have come to replace these expressions. This doesn't mean that an English speaker has no idea of what the words mean - but, again, they do not understand these words in the manner of the Church.