1. Not required by rule or law
   - nonmandatory

See also: optional

• functionally illiterate
• functionary
• functioning
• fund
• fund-raising campaign
• fund-raising drive
• fund-raising effort
• fundament
• fundamental
• fundamental analysis
• fundamental frequency
• fundamental interaction
• fundamental law
• fundamental measure
• fundamental particle
• fundamental principle
• fundamental quantity
• fundamentalism
• fundamentalist
• fundamentalistic
• fundamentally
• fundamentals
• fundamentals analysis
• funded
• fundholder