🧦❓

#unpaired #odd sock #missing pair #single object #incomplete set #uneven

📦➖❓

#missing item #subtracted #removed #incomplete set #not in box #item absent #content missing

🍎🍎　🍎

#incomplete set #something missing #not all there #lacking item #gap in sequence

🟦🟦⬜️🟦

#missing element #gap in sequence #incomplete set #one missing