Pleonasm is the use of more words than necessary to express an idea. This often involves using two words with similar meanings, sometimes called synonyms, in close proximity.
Examples:
* "He was very, very tired." (The repetition of "very" emphasizes the tiredness)
* "The bright, shining sun" (Both "bright" and "shining" indicate light)
* "I saw it with my own eyes." (The phrase "my own eyes" is redundant as "saw" implies the use of eyes)
However, it's important to note that pleonasm is often used for emphasis or to create a specific effect. While it can be considered grammatically incorrect in formal writing, it can be used effectively in informal speech or literature for stylistic reasons.