life·span also life span 
(līfspăn′)
(līfspăn′)n.
1. A lifetime.
2. The average or maximum length of time an organism, material, or object can be expected to survive or last.
- isoantigenicity
- isobar
- isobaric
- isocarboxazid
- isochromatic
- isochronal
- isochronally
- isochronism
- isochronize
- isochronous
- isochroous
- isoclinal
- isoclinally
- isocline
- isoclinic
- isoclinic line
- Isocrates
- isocyanate
- isocyanic acid
- isodiametric
- isodimorphism
- isodynamic
- isodynamic line
- isoelectric
- isoelectronic