any of the various theories or doctrines or philosophical systems that attempt to explain the phenomena of the universe in terms of some immanent force or energy
the quality of being difficult to do; "he assigned a series of problems of increasing hardness"; "the ruggedness of his exams caused half the class to fail"
the property of being rigid and resistant to pressure; not easily scratched; measured on Mohs scale
high level or degree; the property of being intense
the amount of energy transmitted (as by acoustic or electromagnetic radiation); "he adjusted the intensity of the sound"; "they measured the station's signal strength"
feelings of great warmth and intensity; "he spoke with great ardor"
intense feeling of love
a feeling of strong eagerness (usually in favor of a person or cause); "they were imbued with a revolutionary ardor"; "he felt a kind of religious zeal"