a. rare. [f. L. arcifini-us (f. arc- (arx) defence, or arcēre to ward + fīnis boundary) + -OUS.] Having a frontier that forms a natural defence. (The exact sense of the word in Latin is disputed.)
1859. in Worcester.
1884. Twiss, Law of Nations, II. 215. A title to Territory by reason of contiguity, in the case of Arcifinious States, so called according to Varro because their territory admits of boundaries fit to keep the enemy out (fines arcendis hostibus idoneos), in other words, of States whose territory admits of practical limits, such as rivers and mountains, is a reciprocal title.
