if ['if, əf] -conj

  1. in the event that
  2. allowing that
  3. on the assumption that
  4. on condition that
  5. whether
    • asked if the mail had come
    • I doubt if I'll pass the course
  6. used as a function word to introduce an exclamation expressing a wish
    • if it would only rain
  7. even though : although perhaps
    • an interesting if untenable argument
  8. and perhaps not even
    • few if any changes are expected
    often used with not
    • difficult if not impossible
  9. condition, stipulation
    • the question...depends on too many if s to allow an answer -- Encounter
  10. supposition

iff ['if-ᵊn(d)-'ōn-lē-,if; 'if, sometimes read with a prolonged f] -conj

  1. if and only if
    • two figures are congruent iff one can be placed over the other so that they coincide

IFF -abbr

  1. identification, friend or foe

if·fy ['i-fē] -adj, n

  1. having many uncertain or unknown qualities or conditions
    • an iffy proposition
  2. of inconsistent or unreliable quality

IFO -abbr

  1. identified flying object