deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE

/ubha- / उभॱ

The pronoun /ubha- means "both". It only takes dual endings —

/ubha- + /au → !**ubhau उभौ

/ubha- + /bhyAm → !**ubhAbhyAm उभाभ्याम्

/ubha- + /os → !**ubhayos उभयोस्

As far as I know it only appears in these three forms — it is never used in /samAsa, unlike /tad-.