sulcus ter·mi·na·lis \-ˌtərməˈnālə̇s\noun (pluralsulci termina·les \-ā(ˌ)lēz\) Etymology: New Latin, literally, terminal groove 1.: a V-shaped groove separating the anterior two thirds of the tongue from the posterior third and lodging the circumvallate papillae 2.: a shallow groove on the outside of the right atrium of the heart