At once and Matter-of-factly

At once adverb - Without delay or hesitation; with no time intervening.

Matter-of-factly and at once are semantically related. In some cases you can use "Matter-of-factly" instead an adverb phrase "At once".

At once and matter-of-factly are semantically related. Sometimes you can use "At once" instead an adverb phrase "Matter-of-factly".