Calamitous means bringing disaster. A calamitous decision, calamitous consequences, a calamitous year.
It is the strongest of the ordinary words for a bad outcome and belongs to decisions and years rather than to events themselves. The Latin behind it is calamity, of uncertain origin.
1adjectivecalamitousBringing disaster.
“The decision to build the city on a flood plain proved calamitous.”
calamitous is a quality.
Latin calamitosus comes from calamitas, disaster, of uncertain further origin.
Proto-Indo-European
*kelh₂- — to beat; to break
Latin
calamitōsus — destructive, disastrous, ruinous, calamitous
French
calamiteux — calamitous
English, today
calamitous
Built from
Borrowed from French calamiteux (“calamitous”) (see -eux, -ous), from Latin calamitōsus (“destructive, disastrous, ruinous, calamitous”), a contraction of calamitātōsus, from calamitās + -ōsus; calamitāt- is the oblique stem of calamitās (“disaster, misfortune, calamity; damage, harm; loss”), from calamis (“damaged”) (ultimately from Proto-Indo-European kelh₂- (“to beat; to break”)) + -tās. by surface analysis, calamity + -ous.
Etymology from Wiktionary, CC BY-SA