phenomenal meaning
ENFR phénoménal 
- AdjectiveCOMmore phenomenalSUPmost phenomenalPREphéno-SUF-al
- COL Very remarkable; highly extraordinary; amazing.
- (sciences) Perceptible by the senses through immediate experience.
- (philosophy) Of or pertaining to the appearance of the world, as opposed to the ultimate nature of the world as it is in itself.
- COL Very remarkable; highly extraordinary; amazing.
Definition of phenomenal in English Dictionary
- Part-of-Speech Hierarchy
- Adjectives
- Morphemes
- Suffixes
- Words by suffix
- Words suffixed with -al
- Words suffixed with -al
- Words by suffix
- Suffixes
- Adjectives
Source: Wiktionary
Grammatically, this word "phenomenal" is an adjective. It's also a morpheme, more specifically, a suffixe.