Which is the correct spelling for a word meaning 'a very large number'?

Correct — A. The word for 'a very large number' is myriad: m-y-r-i-a-d.

Three checks fix it. The first vowel is y, not i. The r is single. The ending is -ad, the ending of Greek number nouns such as monad, dyad and triad.

It comes from Greek myrias, ten thousand, a figure English stretched to mean countless → option (a).

Why the others are wrong

• (b)
  Myriod — Myriod swaps the a of the ending for an o, giving -iod as in period. The ending shared by number nouns like dyad and triad is -ad.
• (c)
  Miriad — Miriad writes i for the first vowel. The Greek letter behind it is upsilon, which English writes as y, the same y as in myth and gym.
• (d)
  Mirriad — Mirriad makes two mistakes: i for the y, and a doubled r. Myriad has one r, as in the Greek myrias.

A spelling item built on a definition tests two things at once: whether you know the word, and whether you know its exact letters. Here 'a very large number' points to myriad; the letters decide the option.

Greek upsilon generally comes into English as y: myth, rhythm, gym, myriad. That settles Miriad and Mirriad at a glance.

The ending -ad belongs to Greek number nouns: monad (one), dyad (two), triad (three). Myriad, ten thousand, is one of the family.

Key facts

• Myriad means a countless or extremely great number.
• It comes from Greek myrias, 'ten thousand'.
• It is used both as a noun (a myriad of stars) and as an adjective (myriad stars).
• Greek upsilon generally appears in English as y, as in myth and rhythm.

Common traps

• Spelling the first syllable as in mirror, which gives the i and the double r of Mirriad
• Changing the ending to -iod on the model of period

No directly related past PYQ was found.