1.noun(usually in the plural) A leading or primary principle, rule, law, or article, which serves as the groundwork of a system; an essential part
"one of the fundamentals of linear algebra"
2.nounThe lowest frequency of a periodic waveform.
3.nounThe lowest partial of a complex tone.
4.nounThe fundamental analysis data.
"While this stock has been trading at a low P/E multiple lately, I think its fundamentals are sound, and consider it a good buy for long-term investors."