cloud nine

The story

The origin of sense 1 (“a state of bliss”) is uncertain; however, the following etymology has been suggested. (This etymology would explain the "nine" aspect, while not being the de novo origin of the "cloud" aspect; the extension of the meteorological idea to an emotional valence would not have been a de novo development, as the association of clouds with dreaminess long predates the 1890s.) * The first edition of the International Cloud Atlas (1896), which defined ten types of cloud, described the ninth type as the cumulonimbus which rises to 10 km (6.2 miles), the highest a cloud can be. Compare cloud seven (“state of complete happiness or euphoria”), which may have originated from confusion of cloud nine with seventh heaven. Sense 2 (“a state of fantastic or impractical dreaming or thinking”) may be due to a confusion between sense 1 and the phrase head in the clouds.