The 't' in 'often' was silent for centuries — the spelling pronunciation was once stigmatized, now standard.
Frequently; many times; in many instances.
From Middle English 'often,' an extended form of Old English 'oft' (often, frequently), with the addition of the suffix '-en' (possibly by analogy with 'seldom' or other adverbs). Old English 'oft' comes from Proto-Germanic *ufta (often), of uncertain deeper etymology. The shorter form 'oft' survives in literary and poetic English, and the 't' in 'often' was
The 't' in 'often' was silent for centuries — it was pronounced 'offen,' like 'soften.' Pronouncing the 't' was considered a spelling pronunciation and was stigmatized by elocution teachers through the 19th century. Today both /ˈɔːfən/ and /ˈɒftən/ are standard, making 'often' one of those rare words where a once-stigmatized pronunciation has become fully accepted