Rishi Jaimini, the author of Purva Mimamsa and Utttara Mimamsa, explains Dharma as:

"Sa hi nisreyasenapumshamsamyunaktitipra-tijaneemahe
tadabhidhiyatechodanalakshnoarihodharmaha"

―"Dharma is that which is indicated by the Vedas as conducive to the highest good."

Shankaracharya‘s definition of Dharma :

Acharya Shankar defines dharma in the following words:

अभ्युदयनिःश्रेयसकारणो चोदनालक्षणो धर्मः

"That which the Sruti (the Vedas) prompts us to do and which will result in our material and spiritual advancement is dharma."

Dharma is that which accomplishes the three tasks of :

1. Keeping the social system in an excellent condition
2. Bringing about worldly progress of every living being
3. Causing progress in the spiritual realm as well

~ Sri Adi Shankaracharya