Final answer:
A suffix is a letter or group of letters added to the end of a word to form a new word or to alter its grammatical function. Examples include -s, -ed, -ness, and -ous, among others, that change words into plurals, past tense forms, states of being, or adjectives.
Step-by-step explanation:
A suffix is a letter or group of letters added to the end of a word to change its meaning or function. In English, there are many suffixes, each with specific meanings and uses. For instance, the suffix -s at the end of a word can denote a plural noun, like in 'contracts', or the third person singular verb form, as in 'constructs'. Other common suffixes include -ed, which indicates the past tense of a verb, and -ness, which transforms an adjective into a noun that denotes a state or quality of being, like 'happiness' from 'happy'.
There are also suffixes that denote an adjective or quality, like -ous, which can be seen in 'courageous'. Suffixes such as -er and -est are used to form comparative and superlative adjectives respectively, like 'faster' and 'fastest'. The suffix -ess is often used to form nouns indicating a feminine role, such as 'hostess' from 'host'. The same word stem can be combined with different suffixes to create multiple related words, like 'foreign' plus -ness to create 'foreignness', showing the adaptability and richness of the English language's system of suffixes.