His doubt about her loyalty was unfounded as she remained faithful.
accusation
Frequency:
65
%
The accusation against him was baseless and quickly dismissed.
rumor
Frequency:
60
%
The rumor about their breakup was groundless as they were still together.
Idiomatic Expressions for causeless
Phrase: causeless fear
Meaning: Fear that is baseless or irrational, lacking a clear cause or reason.
Usage: She couldn't shake off the causeless fear that gripped her whenever she was alone at night.