Late 19th century; earliest use found in The Times. From philo- + Semitic, probably after anti-Semitic (although this is apparently first attested very slightly later).
Definition of philo-Semitic in US English:
philo-Semitic
adjectiveˌfɪlə(ʊ)sɪˈmɪtɪk
Supportive of or favouring Jews.
Origin
Late 19th century; earliest use found in The Times. From philo- + Semitic, probably after anti-Semitic (although this is apparently first attested very slightly later).