adverb, adverb taking the 'to' particle
obsessively; intensely focused on one thing
Describes single-minded, almost compulsive concentration on a particular activity or goal, often to the exclusion of everything else. Used adverbially with と or as an adverb.
彼は試験勉強にがりがりと取り組んでいる。
He is obsessively studying for the exam.
がりがり働いて、ついに目標を達成した。
She worked intensely and finally achieved her goal.
na-adjective
selfish; self-serving
Used as a na-adjective to describe a person who is ruthlessly self-interested, always putting their own needs first. Often carries a negative, critical tone.
彼はがりがりな性格で、他人のことは考えない。
He has a selfish personality and doesn't think about others.
がりがりに自分の利
They pursue only their own interests in a self-serving way.
A mimetic word (擬態語) derived from the reduplicated sound がり, suggesting a grinding or scraping intensity. The kanji 我利我利 is ateji, chosen for its phonetic value and the meanings of the individual characters (我 'self', 利 'profit'), which reinforce the selfish sense.