We found one dictionary that defines the word plain as the nose on one's face:

General (1 matching dictionary)

1. plain as the nose on one's face: Wiktionary

Definitions from Wiktionary (plain as the nose on one's face) ▸ adjective:  (simile) Synonym of plain as day. ▸ Words similar to plain as the nose on one's face ▸ Usage examples for plain as the nose on one's face ▸ Idioms related to plain as the nose on one's face ▸ Wikipedia articles (New!) ▸ Popular nouns described by plain as the nose on one's face ▸ Words that often appear near plain as the nose on one's face ▸ Rhymes of plain as the nose on one's face ▸ Invented words related to plain as the nose on one's face