An odious number has an odd number of 1s in its binary expansion. For example, 7 = 111 has three 1-bits, so 7 is odious. The complementary set are the evil numbers (even popcount).
The Thue–Morse sequence takes value 1 exactly on the odious numbers. The pair of names is a deliberate pun on odd/even, introduced in combinatorial game theory where the parity of binary digits decides winning strategies in several impartial games.