ˈræʃənl adj. 1 of or based on reasoning or
reason. 2
sensible,
sane,
moderate;
not foolish or
absurd or
extreme. 3 endowed
with reason, reasoning. 4 rejecting
what is
unreasonable or
cannot be tested by reason in
religion or
custom. 5
Math. (of a
quantity or ratio) expressible as a
ratio of
whole numbers. ørational
dress hist. a
style of dress adopted by
some women in
the late nineteenth
century, including
bloomers or knickerbockers. rational
horizon see HORIZON 1c. øørationality n. rationally adv. [ME f. L rationalis (as RATION)]