If you have the sound ji but not the character, here are the 4 characters read this way: 鸡 (jī, chicken, fowl, rooster), 急 (jí, urgent, anxious, hasty, rapid), 己 (jǐ, oneself, self, the sixth Heavenly Stem), 记 (jì, to remember, to record, a mark). They split across 4 tones, so the tone is what separates them.