stubbornly honest; rigidly upright
Describes a person who is so honest and principled that they are inflexible or uncompromising. Often carries a nuance of being too straight-laced.
He has a stubbornly honest personality and cannot tell a lie.
The more rigidly honest a person is, the more likely they are to clash with others at times.
Means stubborn or obstinate on its own. 正直一徹 combines this with honesty to mean stubbornly honest.
Simply means honest or frank. 正直一徹 adds the nuance of inflexibility.
Compound of 正直 (honest) and 一徹 (stubborn, obstinate). The exact historical derivation is uncertain, but the combination yields the meaning of being uncompromisingly honest.