n. 25B6; adjective
a complex situation : COMPLICATED, involved, intricate, convoluted, elaborate, impenetrable, Gordian; difficult, knotty, tricky, thorny; Brit. informal fiddly.
a complex structure : COMPOUND, composite, multiplex.
simple.
25B6; noun
a complex of roads : NETWORK, system, nexus, web, tissue; combination, aggregation.
(informal) he had a complex about losing his hair : OBSESSION, fixation, preoccupation; neurosis; informal hang-up, thing, bee in one's bonnet.