1. A challenge to defend what someone has said
   - demand for explanation

Type of: challenge

• fossilized
• fossilology
• fossorial
• fossorial foot
• fossorial mammal
• foster
• foster care
• foster family
• foster father
• foster home
• foster mother
• foster parent
• foster-brother
• foster-child
• foster-daughter
• foster-nurse
• foster-sister
• foster-son
• fosterage
• fostering
• fosterling
• fothergilla
• FOTS
• Foucault
• Foucault pendulum