Synonyms for Hilly:

adj.

bumpy (adjective)
craggy, mountainous, rangy, rocky, rolling, rugged, sloping, steep, uneven, Undulating.
irregular (adjective)
irregular.
mountainous (adjective)
alpine, mountainous.
rolling (adjective)
Undulating.
rotating (adjective)
rolling.

n.

gentle, gently, graded, gradual, highland. bumpy (noun)
abrupt, broken, irregular, precipitous, rangy, rocky, rolling, rugged, sloping, steep, uneven, Undulating.
hilly (noun)
cragged, craggy, mountainous, rough, unsmooth.

Other synonyms:

gently, graded, gradual, rugged. highland, rolling. irregular, steep. Other relevant words:
abrupt, broken, cragged, craggy, gently, graded, gradual, highland, irregular, precipitous, rangy, rocky, rolling, rough, rugged, sloping, steep, uneven, unsmooth, Undulating.

Usage examples for hilly

  1. Thus, where canals are carried over surfaces that are too hilly and uneven to admit of one continued level, they descend from place to place, as it were by steps, at each of which is an inclined plane; the height from the upper canal to the lower being generally from six to ten feet; and the angle of the plane from forty- five to fifty degrees. – Travels in China, Containing Descriptions, Observations, and Comparisons, Made and Collected in the Course of a Short Residence at the Imperial Palace of Yuen-Min-Yuen, and on a Subsequent Journey through the Country from Pekin to Canton by John Barrow
  2. Just a hilly ridge. – A Letter of Credit by Susan Warner
  3. They kept along the hillside until they struck the track - for it could scarcely be called a road - leading from the village into the interior, and then boldly followed this; for the difficulty of travelling across the hilly and broken country was so great that they preferred to run the slight extra risk of keeping to the road, feeling certain that for the first day's march at least their appearance and the fish they carried would answer for themselves with any body of troops they might meet. – Bonnie Prince Charlie A Tale of Fontenoy and Culloden by G. A. Henty