Gracious
Janissa is a modern American invention, likely created by combining the name Jane or Jan with the popular suffix -issa. It ultimately derives from the Hebrew name Yochanan, meaning 'God is gracious'.
Less common today
Janissa isn't in the latest US Top 1000. It last peaked at #3,982 in 1994.
US births per 5-year period, 1990βpresent (SSA data).