If you have the sound wu but not the character, here are the 5 characters read this way: 屋 (wū, room, house, dwelling), 无 (wú, nothing, without, non-being), 五 (wǔ, five; the organizing number of correlative cosmology), 武 (wǔ, martial, military, valiant), 物 (wù, thing, object, matter, being). They split across 4 tones, so the tone is what separates them.