probably isn't (doesn't, won't, etc.)
Verb dictionary form +
Used with the dictionary form of a verb to express negative volition or negative conjecture. It translates to 'will not' or 'probably will not'.
Verb
Attach
飲む
will probably not drink
見る
will probably not see
This is typically used in formal or written Japanese. It can mean either a strong personal intention not to do something (I will not) or a formal guess that someone else will not do something (they probably won't).
い-Adjective stem + くはある
Used with い-adjectives to express negative conjecture, meaning 'is probably not'.
い-Adjective
Remove the final い from the adjective and attach くはある
新しくはある
is probably not new
寒くはある
is probably not cold
This form is highly formal and literary. In everyday conversation, people usually prefer combining the plain negative form with a standard conjecture expression, such as '〜ないだろう'.
な-Adjective stem or Noun + ではある
Used with な-adjectives and nouns to express negative conjecture, meaning 'is probably not'.
な-Adjective
Attach ではある
便利ではある
is probably not convenient
Noun
Attach ではある
学生ではある
is probably not a student
Like the adjective forms, this construction sounds very formal and is mostly found in literature, written texts, or formal speeches.