Lightheadedness rhymes with:
handedness, blessedness, crookedness, handedness, preparedness, vividness, wickedness, awkwardness, backwardness, badness, baldness, blandness, blessedness, blindness, bloatedness, boldness, coldness, crookedness, discontentedness, fadness, farsightedness, fondness, goodness, handedness, hardness, high-spiritedness, kindness, low-spiritedness, madness, mindedness, nearsightedness, poor-spiritedness, preparedness, public-spiritedness, redness, rudeness, sadness, sandness, shrewdness, soundness, spiritedness, vividness, weirdness, wickedness, wildness
Lightheadedness sounds like:
lactating, lasting, legitimacy, legitimize, legitimizes, lightening, lightens, lighting, lighting's, lightness, lightning, lightnings, liquidating, liquidations, listening, listens, listing, listings, locating, locations, lusitania's, lusitanias, lusting