Definition from Wiktionary, the free dictionary
- Observe the height, that is, at twelve a clocke to take the height of the Sunne, or in the night the North star, or in the forenoone and afternoone, if you misse these by finding the Azimuth and Alnicanter. — The Travels of Captaine John Smith 
- ... old Colonel Robotham would surely do him to death upon discovering that Miss Lucy was wed not to the Poet Laureate at all, but to a servingman, whose astrolabe had already taken the alnicanter of her constellation. — John Barth, "The Sot-Weed Factor"