cursory
idiosyncratic
onus
adventitude
dyadic
murmuration
egalitarian
tractable
nonplussed
tenet
posthumous
ornery
contrariwise
sectarian
oeuvre
nebulous
truculent
halcyon
bibulous
bucolic
oeuvre
extemporaneous
argot
concomitant
reify
exogenous
remit
putative
prosodic
pithy
vitiate
anaemic
malaise
sepulchral
kibosh
off-kilter
maven
impinge
ecumene
mantra
ameliorate
tchotchke
ignominy
laicism
kitschy
febrile
lambast
seraph
behoof
juncture
macabre
amorphous
cloyingly
insipid
sanguine
facile
egalitarianism
pontificate
dogma
verve
capitulate
abstruse
sojourn
cataphora
abstemious
heterodox
perforce
mellifluous
crepuscular

cesium clock: an ultra-precise atomic clock that uses the electromagnetic frequency (9,192,631,770 Hz) produced by the resonance of caesium-133 atoms to define the SI second

apocryphal: probably not true but often believed by people to have happened