哥哥 (gē ge) means older brother. Chinese kinship terms distinguish relative age: 哥哥 is an older brother while 弟弟 (dì di) is a younger brother. The second syllable is often neutral-toned in speech. 哥 alone is also used as a form of address for older male acquaintances or friends (大哥, big bro). In modern slang 哥哥 can be used affectionately for any admired older male. The four sibling terms are 哥哥, 弟弟, 姐姐, 妹妹 (older brother, younger brother, older sister, younger sister).