noun
Usage: usually capitalized S
Etymology: after T. H. Sumner
: a method of determining one's position on the earth in which two approximate latitudes or longitudes are assumed (as from the dead reckoning), the corresponding longitudes or latitudes are calculated from an observation of a heavenly body with the point of observation being somewhere in the line joining the points so determined, and a similar line is determined from another heavenly body or from a later observation of the same body with the intersection of the two lines fixing the point of observation