The form of adjectives (and some adverbs) that ends in -er (e.g. quieter, faster). Sometimes a periphrastic form is used, e.g. more competent (rather than *competenter). See also superlative.
Inflection is the process by which a single word takes different forms. For example, if we have the noun cat, we can add a plural ending to it to create cats. This is known as inflecting a noun and the ending we add is called a suffix.
A very simple definition of adjectives that has sometimes been used is that they are ‘descriptive’ words. But this isn’t really very helpful. Lots of word classes can be ‘descriptive’: a noun like funeral is fairly descriptive, as is the verbleap. We might also say that the adverb quickly describes the verb ran in a sentence like He quickly ran.