Sonji is of African origin, derived from the Swahili word 'sonsundo', meaning 'thankful'. It is a unisex name but more commonly used for females. Sonji gained popularity in the United States during the 1970s and has since been associated with individuals who embrace their heritage and express gratitude.
"Sonji saw a notable rise in popularity between 1964 and 1967, with the number of births more than doubling each year during this period, peaking at 225 births in 1966. However, the name's usage declined significantly afterwards, dropping to single digits by 1970 and remaining relatively uncommon thereafter."