/ ˈmɜːsɪfəli; NAmE ˈmɜːrs-/ adverb
1.
used to show that you feel sb/sth is lucky because a situation could have been much worse
SYN thankfully :
Deaths from the disease are mercifully rare.
Mercifully, everyone arrived on time.
2.
in a kind way :
He was treated mercifully.