A glaucologue was an orator from the early era of the Tutin Empire. At the time of the series it has become a term of reproach for officials who use who use honeyed words to sway their listeners and otherwise abuse their rhetorical gifts to manipulate or frustrate. Europe refers to Secretary Sicus as one at the the court martial at Winstermill; later, in an ironic twist, Sicus attends her come-as-you-fancy ball in glaucologue costume; which appears to involve an olive wreath and something like a toga.
As Tutin approximates real-world Latin (which borrowed may words from ancient Greek), the correct translation of "glaucologue" is something like "bright-words" or "shining-speech", from the Greek gloukos and logos. It may be that the author intended for the reference to be gleukos, or sweet (wine), however it is translated s "sweet-talker."