American Heritage Dictionary
(2)
Century Dictionary
(2)
GNU Webster's 1913
(1)
WordNet
(1)
Elsewhere on the web
Among the less pleasing sounds that fill the welkin are the tonk_, tonk_, tonk of the coppersmith, the kutur_, kutur_, kuturuk of the green barbet, and the calls of the various cuckoos that summer in the plains of Northern India.— A Bird Calendar for Northern India
The fame of Ganga has spread all over the welkin, and Heaven, and Earth, and all the points, cardinal and subsidiary, of the compass.— The Mahabharata of Krishna-Dwaipayana Vyasa, Volume 4 Books 13, 14, 15, 16, 17 and 18
What the virgin Gayatri has said from the welkin is not true.— The Mahabharata of Krishna-Dwaipayana Vyasa, Volume 4 Books 13, 14, 15, 16, 17 and 18
Filling the welkin, the cardinal points of the compass, the subsidiary ones, the firmament, and the Earth, with the whizz of arrows, the twang of bow-strings, the sound of palms, and the clatter of car-wheels, foes rushed upon foes.— The Mahabharata of Krishna-Dwaipayana Vyasa, Volume 3 Books 8, 9, 10, 11 and 12

American Heritage Dictionary (1)
Century Dictionary (1)
Bubble size: how much this word was used in a year
Bubble height: used more or less than expected, vs. all uses evenly distributed
You can expect to see this word several times a year.