sub·phy·lum 
(sŭbfī′ləm)
(sŭbfī′ləm)n. pl. sub·phy·la (-lə)
A taxonomic category of related organisms ranking below a phylum and above a class.
- unflinchingness
- unfocused
- unfocussed
- unfold
- unfoldment
- unforeseen
- unforgettability
- unforgettable
- unforgettableness
- unforgettably
- unforgivable
- unforgiving
- unformatted
- unformed
- unfortunate
- unfortunately
- unfounded
- unfoundedly
- unfoundedness
- unfreeze
- unfrequented
- unfriend
- unfriended
- unfriendliness
- unfriendly