Truckle \TRUHK-uhl\ , intransitive verb;
1. To yield or bend obsequiously to the will of another; to act in a subservient manner
1. A small wheel or roller; a caster
The verb version of this word dates to the 1610's and used to mean "sleep in a truckle bed." The current meaning, implying tameness, may be in allusion to the type of bed that servants and inferiors used. It may also be simply because that kind of bed was lower than a typical one.
The noun version dates to the late 14th century from Anglo-French trocle, which derives from Latin trochlea ("a small wheel, sheaf of a pulley"). Trochlea is a borrowing from Greek trokhileia ("a pulley"), which comes from trokhos ("wheel") from trekhein ("to run"). The Proto-Indo-European root of all this *dhregh- ("to run"). The truckle bed mentioned above dates to the mid-15th century. Trekhein and trokhos are most likely also the forebears of truck.
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Friday, March 18
Etymologies come from the Oxford English Dictionary and/or Etymonline.com