[thank-you-ma'am] n [prob. fr. its causing a nodding of the head] (1849): a bump or depression in a road; esp: a ridge or hollow made across a road on a hillside to cause water to run off
THANK-YOU-MA'AM
Meaning of THANK-YOU-MA'AM in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012