1.
physiological; relating to bodily functions
Relating to the normal functions of a living organism. Used in scientific and medical contexts.
生理的な反応だ。
It's a physiological reaction.
睡眠は生理的に必要なものだ。
Sleep is a physiological necessity.
空腹は生理的な欲求の一つである。
Hunger is one of the physiological needs.
2.
instinctive; visceral; gut-level
Describing a reaction that is automatic and beyond rational control — an instinctive like or dislike. Often used to express strong, involuntary aversion.
生理的に無理だ。
I just can't stand it — it's visceral.
あの人が生理的に受け付けない。
I have a gut-level aversion to that person.
虫が生理的に苦手で、見るだけで鳥肌が立つ。
I have an instinctive aversion to bugs — just seeing them gives me goosebumps.
Sense 2 is very common in everyday Japanese. 生理的に無理 (viscerally impossible/unbearable) and 生理的に受け付けない (can't tolerate on a gut level) are set phrases expressing strong involuntary aversion. This usage implies the reaction is beyond logic or reason — the speaker physically cannot tolerate something. Common collocations: 生理的な欲求 (physiological need), 生理的食塩水 (physiological saline).