lin‧e‧ar /ˈlɪniə $ -ər/ adjective

1. consisting of lines, or in the form of a straight line:
a linear diagram

2. [only before noun] relating to length:
linear measurements

3. involving a series of connected events, ideas etc, that move or progress from one stage to the next:
linear thinking
—linearly adverb
—linearity /ˌlɪniˈærəti, ˌlɪniˈærɪti/ noun [uncountable]
⇒ lateral thinking

[TahlilGaran] Dictionary of Contemporary English ▲