Which one of the following words can be used as a substitute for the phrase, “That which cannot be taken by force”?

Correct — D, (d) Impregnable.

The printed phrase is a definition with its headword removed, and the headword is a word that literally says what the phrase says. ‘Impregnable’ came into English from Old French imprenable, built on prendre, to take, from Latin prehendere — so the word means, piece by piece, ‘not able to be taken’. Its home is fortification: an impregnable fort is one that cannot be carried by assault, however long it is besieged, and from that the word passed to any position that cannot be broken into or broken down, so that an argument, a defence or a lead in a match may be described as impregnable.

The spelling is worth a note, because it misleads. The ‘g’ is a later insertion and belongs to no part of the word’s history; ‘impregnable’ has nothing to do with ‘impregnate’, which comes from Latin praegnans, pregnant. Candidates who try to read the sense off the modern spelling are reading a letter that was never in the word.

What makes this item easy once seen is that all four options are built on the same negative prefix, in- appearing as im- before a p. So the prefix decides nothing at all and the whole question lies in the root: posse, to be able, gives impossible; probare, to prove or test, gives improbable; peccare, to sin, gives impeccable; prendre, to take, gives impregnable. Only the last of the four roots is the verb the printed phrase uses — ‘cannot be taken’ — and the phrase even names the means, by force, which is the assault an impregnable place withstands.

One caution about reading the stem: the word ‘cannot’ sits inside the phrase being defined, not in the instruction. The instruction is the plain positive one of finding the word that substitutes for the phrase.

Why the others are wrong

• (a)Impossible — ‘Impossible’ is from Latin posse, to be able, and means simply that a thing cannot be done or cannot happen. It is far too wide for the printed phrase, which does not say that the thing cannot be got at all — only that it cannot be got by force. An impregnable fort may perfectly well be taken by starvation, by treachery or by negotiation, and the phrase leaves all of those open; ‘impossible’ would shut them. A definition item is answered by the word that covers exactly the ground described, and the option that covers more ground than the phrase is as wrong as the option that covers less.
• (b)Improbable — ‘Improbable’ is from Latin probare, to test or prove, and it grades likelihood: what is improbable is unlikely to be true or to happen, though it may still do either. The printed phrase is not about likelihood at all; it says the thing cannot be taken, which is a statement about capacity. The gap between the two is the everyday gap between ‘it probably will not’ and ‘it cannot’, and examiners exploit it regularly because both words feel like denials. Note also that ‘improbable’ is about the event, while the phrase describes a thing — ‘that which…’ — and asks for a quality belonging to it.
• (c)Impeccable — ‘Impeccable’ is from Latin peccare, to sin, so it means literally not liable to sin and, in ordinary use, faultless: impeccable manners, an impeccable record, impeccable credentials. It is a word of praise for conduct or workmanship and says nothing about resisting capture. It is the most attractive of the three misses because it is the least common word on the page after the answer, and a candidate who is choosing the unfamiliar option on the assumption that the paper wants a hard word will land on it. The root, not the rarity, decides.

This item teaches a method that answers a large class of vocabulary questions: take the word apart. A great deal of formal English is built from a Latin or Greek root with a prefix in front and a suffix behind, and when four options share a prefix — as all four do here — the prefix is not the question, the root is.

The negative prefix in- assimilates to the consonant that follows it, which is why the same prefix appears as im- before p, b and m (impossible, imbalance, immortal), as il- before l (illegal), as ir- before r (irregular) and as in- elsewhere (invisible). Recognising that these are one prefix rather than five saves a candidate from treating the spelling as a clue.

The roots in play here are all productive in English and worth collecting. Prehendere or prendre, to take or seize, gives apprehend, comprehend, prehensile, prison, prey, enterprise and surprise, which is literally an overtaking. Posse, to be able, gives possible, potent, puissant and power. Probare, to test, gives probable, probe, probation, approve and proof. Peccare, to sin, gives impeccable and peccadillo, a small sin.

The second lesson is about the fit of a definition. The right word matches the whole of the printed phrase and no more of it: ‘cannot be taken by force’ is narrower than ‘cannot be done’ and quite different from ‘is unlikely’.

Key facts

• ‘Impregnable’ comes from Old French imprenable, on prendre, to take, from Latin prehendere; it means literally ‘not able to be taken’, first of a fortress and then of any position.
• The ‘g’ in the modern spelling was inserted later and is not part of the word’s history; ‘impregnable’ is unrelated to ‘impregnate’, which is from Latin praegnans.
• All four options carry the same negative prefix in-, which appears as im- before p, so the discrimination lies entirely in the roots.
• The roots are posse, to be able (impossible); probare, to test or prove (improbable); peccare, to sin (impeccable); and prendre or prehendere, to take (impregnable).
• ‘Impossible’ is wider than the phrase, which denies only capture by force and leaves siege, treachery or negotiation open; ‘improbable’ grades likelihood rather than capacity.
• The negative in this stem belongs to the phrase being defined, not to the instruction, which asks positively for the word that substitutes for it.

Common traps

• Choosing the least familiar option on the theory that the paper wants a hard word. Here the roots decide, and the rarest-looking option is not the answer.
• Reading the modern spelling of the answer as though it were related to ‘impregnate’, and rejecting it for a resemblance that is an accident of the sixteenth century.
• Taking ‘impossible’ because the phrase contains ‘cannot’. The phrase denies capture by force only, and the word must match the whole of it and no more.
• Reading the ‘cannot’ inside the quoted phrase as part of the ask; the instruction is a positive one about which word substitutes.

• practice — not a real PYQ

  Which one of the following words can be used as a substitute for the phrase, “That which cannot be conquered or defeated”?

  • (a)Invisible
  • (b)Invincible
  • (c)Invaluable
  • (d)Inevitable

  Answer(b) Invincible — from Latin vincere, to conquer, so literally not conquerable. ‘Invisible’ is from videre, to see; ‘invaluable’ means too precious to be valued; and ‘inevitable’ is from evitare, to avoid, so it means unavoidable.

• practice — not a real PYQ

  Which one of the following words can be used as a substitute for the phrase, “That which cannot be rubbed out or erased”?

  • (a)Incredible
  • (b)Incorrigible
  • (c)Indelible
  • (d)Ineligible

  Answer(c) Indelible — from Latin delere, to blot out, the root also of ‘delete’, so an indelible mark cannot be erased. ‘Incredible’ cannot be believed, ‘incorrigible’ cannot be corrected, and ‘ineligible’ cannot be chosen.