pre-noun adjectival
a certain; some
Pre-noun adjectival (rentaishi) used to refer to an unspecified but particular person, thing, or place. Always modifies a noun directly.
One day, I suddenly got a call from him.
ある意味では、彼の言うことも正しい。
In a certain sense, what he says is also correct.
One day, he suddenly called me.
At one point, he suddenly said he was going to quit his job.
What he says is, in a sense, correct.