Select the INCORRECTLY spelt word.

Correct — D. The word intended is verifiability, the noun formed from verifiable.

Verify ends in a consonant plus y, so the y turns to i before a suffix: verify → verifiable → verifiability. The suffix is -able, which makes the noun -ability.

The printed form drops the a and gives -ibility, so option (d) is the incorrectly spelt word. The other three are printed correctly, unusual as two of them look.

Why the others are wrong

• (a)
  Voluptuous — Voluptuous is spelt correctly, on the -uous pattern of sumptuous and presumptuous. The item asks for the misspelling, so a correctly spelt word cannot be marked.
• (b)
  Vomitus — Vomitus is a real and correctly spelt word: the medical noun for vomited matter. Its Latin -us ending looks odd, which is exactly why it attracts guesses.
• (c)
  Verminous — Verminous is correct — vermin plus the adjective suffix -ous, meaning infested with or suggestive of vermin. Nothing in it needs changing.

Two spelling rules meet in this word.

First, a verb ending in a consonant plus y changes that y to i before a suffix: verify → verifiable, rely → reliable, apply → appliance.

Second, the suffix is -able, not -ible. As a working rule, -able attaches to something that can stand alone as an English word (verify, accept, comfort), while -ible usually attaches to a Latin stem that cannot (audible, visible, tangible).

A word built with -able takes -ability as its noun, so verifiability keeps the a.

Key facts

• The correct spelling is verifiability, from verify and verifiable.
• A verb ending in consonant plus y changes y to i before a suffix, as in rely → reliable.
• -able normally follows a free-standing English word, while -ible normally follows a bound Latin stem such as aud- in audible.
• Vomitus is the medical noun for vomited matter and is spelt as printed.

Common traps

• Marking an unfamiliar word such as vomitus because you have not met it before.
• Missing the dropped a, since verifibility and verifiability sound nearly identical when read at speed.
• Answering the usual question and picking the correctly spelt word.

No directly related past PYQ was found.