1. Having no justifying cause or reason
   "a senseless, causeless murder"; "a causeless war that never had an aim"
   - reasonless 
2. Having no cause or apparent cause
   "a causeless miracle"
   - fortuitous, uncaused

See also: unintended, unmotivated

• rate of inflation
• rate of interest
• rate of pay
• rate of payment
• rate of respiration
• rate of return
• rateability
• rateable
• rateables
• ratel
• ratepayer
• rater
• rates
• rathe
• rather
• rathole
• rathskeller
• Ratibida
• Ratibida columnaris
• Ratibida columnifera
• Ratibida tagetes
• ratification
• ratified
• ratifier
• ratify