Phenomenal means remarkable to an extraordinary degree. Phenomenal success, a phenomenal memory, phenomenally cheap.
In everyday use it is simply a strong word for outstanding. In philosophy it means quite different: relating to what appears to the senses, as against the thing in itself, which is Kant's distinction and the original sense of the word.
1adjectivephenomenalRemarkable to an extraordinary degree.
“Her first novel was a phenomenal success and sold all around the world.”
phenomenal is a degree of excellence.
From phenomenon plus -al, from Greek phainomenon, a thing appearing, from phainein, to show.
French
phénoménal
English, today
phenomenal
From phenomenon + -al. From phenomenon + al, after French phénoménal.
Etymology from Wiktionary, CC BY-SA