contern.are V 1 1 PRES ACTIVE INF 0 X
contern.are V 1 1 PRES PASSIVE IND 2 S Early
contern.are V 1 1 PRES PASSIVE IMP 2 S
conterno, conternare, conternavi, conternatus V (1st) TRANS [XXXFO] veryrare
divide into groups of three; (persons);
Syncope r => v.r
Syncopated perfect often drops the 'v' and contracts vowel
conternav.ere V 1 1 PERF ACTIVE IND 3 P
conterno, conternare, conternavi, conternatus V (1st) TRANS [XXXFO] veryrare
divide into groups of three; (persons);

Credits:
This, our local install of the popular standby Whitaker's Words, is possible thanks to the resurrection of the venerable project at William Whitaker's Words, where you will also find extensive documentation. The corresponding GitHub repository is where you can submit issues about missing forms and analyses.
This web interface by Walter M. Shandruk.