Verb (5-dan, る, intransitive)
1.  to reach an extreme;  to reach a limit;  to terminate;  to come to an end
Pre-noun adjective
Auxiliary verb (5-dan, る)
2.  extremely
after adjectival noun. e.g. 退屈極まる話
Verb (5-dan, る, intransitive)
3.  to be stuck;  to be in a dilemma;  to be at a loss
esp. 窮まる. occ. 谷まる
4.  to be decided;  to be settled