- isurus glaucus
- isurus oxyrhincus
- it all depends
- it depends
- isogram
- isolated
- isolator
- isolationist
- isolde
- isomerisation
- isole egadi
- isomerization
- isometric
- isometric exercise
- isometric line
- isometrics
- isomorphic
- isomorphous
- isopoda
- isopleth
- isoniazid
- isomorphy
- isoptera
- isopropanol
- isopyrum
- isopropyl alcohol
- isoroku yamamoto
- isosceles traiangle
- isospondyli
- isosmotic
- isosmotic solution
- isotope
- isotonic
- isotonic exercise
- isotonic solution
- isotopic
- it figures
- it is a good thing that
- it is just as well
- it is about time
- it is high time
- it is some sort of support
- it is the early bird that catches the worm
- it is the harvest that proves the farmer
- it is work that makes a workman
- it just so happens that
- it is hard to sit in rome and strive against the pope
- it makes no odds
- it never rains but it pours
- it may be death to one and not even fun to another