1. (of rules) stringently enforced
   "hard-and-fast rules"
   - strict

See also: invariable

• unspeakably
• unspecialised
• unspecialized
• unspecific
• unspecified
• unspectacular
• unspell
• unspent
• unspoiled
• unspoilt
• unspoken
• unspoken accusation
• unsporting
• unsportingly
• unsportsmanlike
• unspotted
• unstable
• unstableness
• unstaged
• unstained
• unstaple
• unstarred
• prestigious
• prestigiousness
• prestissimo