1. Not required by rule or law
   - nonobligatory

See also: optional

• essentially
• essentialness
• Essex
• Essex girl
• essonite
• EST
• establish
• established
• established church
• establishment
• establishmentarian
• establishmentarianism
• establishmentism
• estaminet
• estancia
• estate
• estate agency
• estate agent
• estate car
• estate for life
• estate of the realm
• estate tax
• Estates General
• estazolam
• esteem