What does Ayush mean?
From Sanskrit ayus (आयुस्), 'life, vital power, long life, longevity'. A blessing-name wishing the child a long life.
What does Ishan mean?
From the Sanskrit ईशान (īśāna), 'ruler, master'. It is an epithet of the god Shiva, also denotes the sun and the north-eastern quarter (one of the dikpalas). A genuine, well-attested Vedic/classical term.