amiss
adj.wrong, bad, or not quite right. You use this when something is slightly off or doesn't feel quite normal.
adj.improper, wrong, or not quite right. Often used in the phrase 'something is amiss' to indicate a sense of unease or a perceived fault.
“Something is amiss with the car engine.”
“The manager noticed something was amiss when the sales figures didn't match the inventory reports.”
“A sense of unease settled over the group as they realized something was amiss with the carefully prepared schedule for the evening's performance.”
“A guard fired two shots to signal that something was amiss, but before he could investigate further, a bugle call pierced the night air.”
“Only the presence of a sailor tasked with protecting Alexei by accompanying him everywhere, even carrying the boy when he was too sick to walk on his own, suggests that something is amiss.”
From a- + miss.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.