Also: "onii-san (お兄さん)", "onii-sama (お兄さま)", "onii-chan (お兄ちゃん)", "nii-sama (兄さま)", "nii-san (兄さん)", "nii-chan (兄ちゃん)"

"Older brother"—one of those very simple terms which is unfortunately difficult to translate because of the differences in usage between English and Japanese. In Japanese, it is much more natural to call your (older) brother "nii-san" or "onii-san" rather than by their given name. It connotates a degree of respect and at the same time a certain closeness. ("Onii-sama" indicates more formality, "onii-chan" indicates less familiarity.) This is the same reason most children in both cultures call their parents "Mom" and "Dad" instead of by their given names.

One can also use "onii-san" to refer politely to an unrelated slightly older male.