Definition - What does Nai-Nitya Karma mean?
Nai-Nitya Karma is Sanskrit for the conditional rituals to be performed by a Hindu, depending on their circumstance. A subdivision of the Nithya Karmas, which are the obligatory rituals that must be performed so as not to commit sin, the nai-nitya karmas are compulsory and do not have to be performed based on the individual.
Yogapedia explains Nai-Nitya Karma
Hindus who follow the Shastras or holy texts perform many rituals to ensure a rich spiritual life and to avoid committing sin. The nai-nitya karmas are a subset or exception to obligatory nithya karmas, the exceptions are for the different circumstances people find themselves in during their lives. The nai-nitya karmas include the grahana karmas. Grahana occurs when there is an eclipse of the moon or the sun. Typically, during this time, one would perform the grahana karmas and include a fast, unless the observer is very young, old or sick. This exception is an example of a nai-nitya karma.