sig ‧ nal ‧ ly /ˈsɪɡnəli/ BrE AmE adverb formal
[ Word Family: noun : ↑ sign , ↑ signal , ↑ signatory , ↑ signature , ↑ signing , ↑ signaller ; verb : ↑ sign , ↑ signal ; adverb : ↑ signally ; adjective : signed ≠ ↑ unsigned ]
very noticeably:
The government has signally failed to deal with the problem.