the ratio of the focal length to the diameter of a (camera) lens system

the relative magnitudes of two quantities (usually expressed as a quotient)

- respiratory quotient
- loss ratio
- abundance
- magnitude relation
- focal ratio
- margin of profit
- proportionality
- relative humidity
- quotient
- load factor
- cephalic index
- betting odds
- gasoline mileage
- Mach number
- gas mileage
- facial index
- index of refraction
- signal-to-noise
- cranial index
- mileage
- signal-to-noise ratio
- breadth index
- loading
- price-to-earnings ratio
- refractive index
- frequency
- average
- S/N
- turnover
- packed cell volume
- odds
- signal/noise ratio
- I.Q.
- magnitude
- intelligence quotient
- stop number
- mechanical advantage
- speed
- hematocrit
- factor of safety
- stoichiometry
- gross margin
- order of magnitude
- employee turnover
- P/E ratio
- quantitative relation
- aspect ratio
- output-to-input ratio
- productivity
- safety factor
- efficiency
- f number
- haematocrit
- IQ
- magnification
- profit margin
- albedo
- reflective power
- fuel consumption rate
- prevalence
- turnover rate
- relative frequency
- signal/noise
- time constant
- eccentricity

having or localized centrally at a focus

the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree