The crossword solution for the term 'ONE OF TWO IN A JACK-O'-LANTERN?' is 'EYES', which refers to the two eye-shaped cutouts that are traditionally carved into a pumpkin to make a Jack-o'-lantern. This practice originated in Ireland and Scotland, where people would carve turnips or potatoes to ward off evil spirits. The tradition was brought to North America by Irish immigrants, who used pumpkins instead of turnips.