Ifとは 意味・読み方・使い方

発音

• enPR: ĭf, IPA^(key): /ɪf/
• 韻: -ɪf

接続詞

if

1. Supposing that, assuming that, in the circumstances that; used to introduce a condition or choice.

   If it rains, I shall get wet.

   I'll do it next year —if at all.

2. (computing) In the event that a statement is true (a programming statement that acts in a similar manner).

   If A, then B, else C.

3. Supposing that; used with past or past perfect subjunctive indicating that the condition is closed.

   I would prefer it if you took your shoes off.

   I would be unhappy if you had not talked with me yesterday.

   If I were you, I wouldn't go there alone.

4. Supposing that; given that; supposing it is the case that.

   If that's true, we had better get moving!

   • 1596, Edmund Spenser, “Book I”, in The Faerie Queene. […], part I (books I–III), London: […] [Richard Field] for William Ponsonbie, →OCLC, stanza ii, page 66:

     O what of Gods then boots it to be borne, / If old Aveugles ſonnes ſo euill heare?

5. Although; used to introduce a concession.

   He was a great friend, if a little stingy at the bar.

   She won her team's admiration, if not its award, for her performance.

6. (sometimes proscribed) Whether; used to introduce a noun clause, an indirect question, that functions as the direct object of certain verbs.

   I don't know if I want to go or not.

   • 1715–1717, Matthew Prior, Alma; or, The Progress of the Mind, Canto III:

     Quoth Matthew, “ […] / She doubts if two and two make four, / […] ”

   • 1976, Michael Harrison, Beyond Baker Street: A Sherlockian Anthology (page 117)

     It is doubtful if the Victorian Londoner needed any warning, for the artful mobsmen, toolers, whizzers and dippers, together with their stickman accomplices, were everywhere in the crowds, in the underground, on railway trains […]

7. (usually hyperbolic) Even if; even in the circumstances that.
   • 1837-39, Charles Dickens, Oliver Twist

     “Wait a minute!” said the girl: “I wouldn’t hurry by, if it was you that was coming out to be hung, the next time eight o’clock struck, Bill. I’d walk round and round the place till I dropped, if the snow was on the ground, and I hadn’t a shawl to cover me.”

   • 2004, David Lee Murphy and Kim Tribble (writers), Montgomery Gentry (singers), “If It’s The Last Thing I Do” (song), in You Do Your Thing (album):

     If it’s the last thing I do / If it takes me from Tubilo to Timbuktu / If it’s the last thing I do / I’m gonna dodge every road block, speed trap, county cop / To get my hands on you / If it’s the last thing I do.

8. Introducing a relevance conditional.

   I have leftover cake if you want some.

使用する際の注意点

• Specifically a subordinating conjunction.
• Some usage critics recommend that if not be used to mean whether, since the distinction can remove ambiguity, as in the following example:

Tell me if you can see her. (if the addressee can see her, then he または she must let the speaker know)

Tell me whether you can see her. (the speaker wants to know which instance is true: either the addressee's ability or inability to see her)

• This distinction is further encouraged because, traditionally, if cannot always be used in place of whether. For instance, if the noun clause acts as the subject of the sentence or an object of a preposition, the word is usually whether. Examples:

We like to talk about whether classical music is better than jazz.

Whether you like today’s weather does not matter.

• Another difference between if and whether is with the use of or not.

The sentences I don't know whether or not I passed or I don't know whether I passed or not are both correct

The sentence I don't know if I passed or not is correct, but I don't know if or not I passed is incorrect

別の表記

• eef (representing various accents)
• ifen, iffen, if'n (dialectal)

派生語

名詞

if (複数形 ifs)

1. (informal) An uncertainty, possibility, condition, doubt etc.
   • 1709, Susannah Centlivre, The Busy Body, Act III, in John Bell (ed.), British Theater, J. Bell (1791), page 59,

     Sir Fran. Nay, but Chargy, if——— ¶ Miran. Nay, Gardy, no Ifs.——Have I refus'd three northern lords, two British peers, and half a score knights, to have put in your Ifs?

   • 1791 January, "Richardſon’s Chemical Principles of the Metallic Arts", in The Monthly Review, R. Griffiths, page 176,

     Well might Bergman add, (in his Sciographia,), “if the compariſon that has been made, &c. be juſt.” The preſent writer makes no ifs about the matter, and has ſuperadded a little inaccuracy of his own, […]

   • 2013 April 9, Andrei Lankov, “Stay Cool. Call North Korea’s Bluff.”, in New York Times‎^[1]:

     Even if they managed to strike Japan, the United States or South Korea with nuclear weapons — a big if, given that they do not have a reliable delivery system — they could not save themselves from ultimate defeat.

派生語

• big if
• ifs and ans
• no ifs, ands, or buts
• small if

参考

• and
• else
• false
• or
• then
• true
• whether

Further reading

• if at OneLook Dictionary Search

アナグラム

• FI, Fi, fi