Smartening rhymes with:
disheartening, heartening, disheartening, heartening, shortening, battening, brightening, captaining, disheartening, enlightening, fattening, flattening, frightening, heartening, heightening, lightening, shortening, straightening, sweetening, threatening, tightening
Smartening sounds like:
samaritans, smarting, smartness, snorting