horizontal

hor·i·zon·tal

adj \ˌhȯr-ə-ˈzänt-^əl, ˌhär-\

Definition of HORIZONTAL

1

: relating to or being a transverse plane or section of the body

2

: relating to or being transmission (as of a disease) by physical contact or proximity in contrast with inheritance—compare vertical

—hor·i·zon·tal·ly \-^əl-ē\ adverb