Hesitant syllables are two-syllable words that are used to express hesitation or uncertainty. The crossword solutions UMS and ERS are both examples of hesitant syllables. UMS is an abbreviation for 'umms' which is a sound made when someone is hesitating or searching for the right words to say. ERS is an abbreviation for 'ers' which is another sound made when someone is hesitating or unsure of what to say. Both UMS and ERS are commonly used in everyday speech to express hesitation or uncertainty.