Definition of "glacially"

‘Monsieur,’ Louis XV glacially remarked to Choiseul days before the dénouement, ‘I told you that I did not want war.’

2002, Colin Jones, The Great Nation, Penguin, published 2003, page 278

Played acoustically, glacially paced and sung in Kristofferson’s parched, age-weathered voice, even his more lighthearted songs – Jesus Was a Capricorn, Best Of All Possible Worlds – were leant an eerie gravitas, while Me and Bobby McGee and Sunday Morning Coming Down sounded heartbreakingly careworn and poignant.

2017 June 26, Alexis Petridis, “Glastonbury 2017 verdict: Radiohead, Foo Fighters, Lorde, Stormzy and more”, in the Guardian‎

The daunting problem is that the incidence of tuberculosis has declined only glacially (at a rate of 1.0 to 1.5% per year) and in some places may be increasing.

2018 January 18, Barry R. Bloom, “A neglected epidemic”, in the New England Journal of Medicine‎, pages 291–3