1. The ratio of the focal length to the diameter of a (camera) lens system
   - focal ratio, f number, speed

Derived forms: stop numbers

Type of: ratio

• stern chaser
• Sterna
• Sterna hirundo
• sternal
• Sterne
• Sterninae
• sternite
• sternly
• sternmost
• sternness
• sternocleido mastoideus
• sternocleidomastoid
• sternocleidomastoid muscle
• sternocleidomastoid vein
• Sternotherus
• sternpost
• sternum
• sternutation
• sternutative
• sternutator
• sternutatory
• sternway
• sternwheeler
• steroid
• steroid alcohol