requirement (n.)

• blackmail
• call
• claim
• condition
• contribution
• demand
• desideratum
• draft
• drain
• duty
• essential
• exaction
• extortion
• imposition
• impost
• indent
• levy
• must
• necessity
• need
• notice
• occasion
• order
• precondition
• prerequisite
• provision
• proviso
• qualification
• requisite
• requisition
• rush
• stipulation
• tax
• tribute
• ultimatum
• want
• warning