In every language with a finite number of words there must be words that are not definable in terms of simpler words/concepts. Perhaps you’ve stumbled upon such a word with “truth”. I think it is obvious what I meant to most people.
I suspect your parent intended to imply that in practice "truth" is largely socially-generated. So your objective definition would be moot.
Not that I'd necessarily agree, its just an interpretation.
A linguistic extension of godels second incompleteness theorem? Interesting.