blue tick1
/ˌbluː ˈtɪk/noun
Any of several cattle ticks of the genus Rhipicephalus and subgenus Boophilus (family Ixodidae); specifically R. decoloratus, which is found mainly in sub-Saharan Africa and transmits babesiosis (redwater), anaplasmosis, and other parasitic diseases in wild and domesticated mammals.
Origin
Mid 19th century; earliest use found in Journal Royal Asiatic Society. From blue + tick, so called because of the blue appearance of the body of the engorged female.
blue-tick2
/ˈbluːtɪk/noun
= blue-tick coonhound.
Origin
1920s; earliest use found in Hunter–Trader–Trapper. From blue + tick.