We found one dictionary that defines the word horizontal surfaces:

General (1 matching dictionary)

1. horizontal surfaces: Vocabulary.com

(Note: See horizontal_surface as well.)

Definitions from WordNet (horizontal surface) ▸ noun:  a flat surface at right angles to a plumb line ▸ Also see horizontal_surface ▸ Words similar to horizontal surfaces ▸ Usage examples for horizontal surfaces ▸ Idioms related to horizontal surfaces ▸ Wikipedia articles (New!) ▸ Words that often appear near horizontal surfaces ▸ Rhymes of horizontal surfaces ▸ Invented words related to horizontal surfaces