noun which may take the genitive case particle 'no', noun
belated; late; eleventh-hour
Describes something done later than expected or appropriate. Most commonly used in the set phrase 遅ればせながら (meaning 'belatedly' or 'better late than never') to apologize for a late action or greeting.
See also: 遅ればせながら (おくればせながら)
遅ればせながら、明けましておめでとうございます。
Belatedly, Happy New Year.
遅ればせの返事で申し訳ありません。
I'm sorry for the belated reply.
Rare spelling combining 後 and 馳; very uncommon.
遅い is a general adjective meaning 'slow' or 'late'. 遅ればせ is a more specific, somewhat formal noun/adjective used almost exclusively in the phrase 遅ればせながら to express a belated action.
Derived from the verb 遅れる (おくれる, 'to be late') and the classical verb 馳す (はす, 'to run'), literally meaning 'running late'. The exact historical derivation is uncertain, but the word has been used since at least the Edo period.