• Basic forms
• 極める — to master; to pursue to the limit / base form
• 極めます — master / masu form
• 極めた — mastered / ta form
• 極めて — master and … / te-form
• 極めない — do not master / negative
• 極めれば — if (one) masters / conditional
• 極めろ・極めよ — master it! / imperative
• Other common forms
• 極めたい — want to master / 〜たい form
• 極められる — can master / potential
• 極められない — cannot master / negative potential
• More
• 技を極める — to master a skill
• 真理を極める — to pursue the truth
• 極めよう — let’s master it / 〜よう form
• 極めなかった — did not master / past negative

極める（きわめる） is an ichidan verb. It expresses actively pursuing something to its limit — mastering a skill, field, or idea. Often used in contexts of study, training, and personal growth.