1. the use of words, phrases, or styles that are old-fashioned or no longer in common use
2. a word, phrase, or expression that is archaic or outdated

Examples

• The poet’s use of archaism gave his work a deliberately old-fashioned feel.
• Words like ‘thou’ and ‘thee’ are examples of archaism in modern English.
• The translation avoided archaism to make the text accessible to contemporary readers.
• His speech was full of archaism that made him sound like he was from another century.
• The deliberate archaism in the fantasy novel helped create an atmosphere of ancient times.
• Critics noted the author’s tendency toward archaism in her historical fiction.