among the South Sea Islanders, means “devoted” in a religious sense. Thus, a temple is tapu, and he who violates a temple is tapu. Not only so, but everyone and everything connected with what is tapu becomes tapu also. Thus, Captain Cook was tapu because some of his sailors took rails from a “temple” of the Hawaiians to supply themselves with fuel, and, being devoted, he was slain Our taboo is the same word.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894