Final answer:
The word 'infallible' is an adjective that describes something as incapable of making mistakes or being wrong, often synonymous with 'flawless' or 'perfect'.
Step-by-step explanation:
The word infallible is an adjective, which is a part of speech that modifies or describes nouns. Adjectives can take on different forms to convey precise meanings, such as using comparative words like more or less, or being combined with qualifiers such as very or extremely. For instance, in the sentence, 'She is looking for a more reliable car,' the word 'reliable' is an adjective that is enhanced by the comparative word 'more' to form an adjective phrase that modifies the noun 'car'. Similarly, the adjective 'infallible' could be used in a sentence like, 'The scientist presented an infallible argument,' where 'infallible' describes the noun 'argument', indicating that it is perfect or faultless and incapable of being wrong.