capriciously

adverb
1
in a way that shows sudden changes in attitude or behaviour without good reason
دمدمی مزاجانه, بی‌ثباتانه, ناپایدارانه
2
in a way that changes suddenly and quickly without an obvious pattern
دمدمی, بی‌ثبات, دمدمی‌مزاجانه, بی‌ثباتانه, غیرقابل پیش‌بینی
The disease spread capriciously, causing some 31 000 estimated deaths.
synonym unpredictably