Gracious; white wave
Jennise is a modern American blend, likely combining the classic Jennifer with the suffix -ise, or acting as a variant of Janice. It draws from the Cornish 'Gwenhwyfar' meaning 'white wave' and the Hebrew 'Yochanan' meaning 'God is gracious'.
Less common today
Jennise isn't in the latest US Top 1000. It last peaked at #10,860 in 1993.
US births per 5-year period, 1990βpresent (SSA data).