～うる / ～える
be possible or conceivable
～うる / ～える (written 得る) attaches to the ます-stem of a verb and means that the event can possibly happen or is conceivable: 起こります becomes 起こりうる, “can occur”. It is a formal, written-style potential.
Unlike the ordinary potential form (読める, “someone is able to read”), this pattern is not about a person's ability. It states an objective possibility: “it could happen”, “it is conceivable”.
1. Stating that something is possible
The affirmative form asserts that an outcome lies within the realm of possibility.
それは十分にあり得る話だ。
“That's a perfectly conceivable story.”
- それ = that
- は = topic marker
- 十分に（じゅうぶんに）= fully, perfectly well
- あり得る（ありえる）= can happen, is conceivable (also read ありうる)
- 話（はなし）= story
- だ = copula (is)
2. The negative ～えない: impossible
The negative is always ～えない, never うない. あり得ない, “impossible, cannot be”, is so common it appears even in casual speech as an exclamation.
そんな話はあり得ない。
“A story like that is impossible.”
- そんな = that kind of
- 話（はなし）= story
- は = topic marker
- あり得ない（ありえない）= impossible, cannot be
A note on reading: the dictionary form can be read うる (more literary) or える, but conjugated forms use え only — あり得ない (ありえない), あり得ます (ありえます).
How to form it
Verb ます-stem + うる / える
- ある = to exist → あり得る（ありうる）= can happen
- 起こる（おこる）= to occur → 起こり得る（おこりうる）= can occur
- 考える（かんがえる）= to think → 考え得る（かんがえうる）= conceivable
Key idea
～うる / ～える measures possibility, not skill. It says an event is within the realm of what could happen. If you mean a person can do something, use the regular potential form. If you mean “such a thing could occur”, use ～うる.
Other N2 grammar
Updated .