Obúr elicits a more general reason, whereas át2 tends to imply cause or purpose.
From Middle Radestrian obôr, from Old Radestrian avbôr, from Proto-Radic *abbôr, from Proto-Hirdic *aḇbɔ̄́s, from Proto-Laenkean *⁂m̥bbáws, from the Proto-Laenkean root *ᵐbæj(n)-(interrogative).
From Middle Radestrian aucíra, from Old Radestrian avcijra, from Proto-Radic *abciǧor, from Proto-Hirdic *aḇkighós, from Proto-Laenkean *m̥bk-igʱó-, from the Proto-Laenkean root *ᵐbik-(to damage, to harm).
From Middle Radestrian audrass, from Old Radestrian awdrass, from Proto-Radic *aǧdorhs(evening), with sporadic shortening, from Proto-Hirdic *ghədɔ̄́rkhəs, from Proto-Laenkean *gʱa-ⁿdawrkʰ-, from the Proto-Laenkean root *ⁿdawrkʰ-(dark/night).
From Middle Radestrian vue-, from Old Radestrian lŭe-, from Proto-Radic *lıe-, from Proto-Hirdic *ləḡe(ḡ)-, from Proto-Laenkean *l̥g-ég-, from the Proto-Laenkean root *log-(five).
From Middle Radestrian auraiș, from Old Radestrian awraišjer, from Proto-Radic *aǧrahs, *aǧrajišjir, from Proto-Hirdic *aḡhrə́həs, from Proto-Laenkean *ŋ̊gh-ŕ̥h-, from the Proto-Laenkean root *ᵑgih-(reflexive).
From Middle Radestrian aurast, from Old Radestrian awræztt, from Proto-Radic *agræhzht, from Proto-Hirdic *aḡrǽp̄z-, from Proto-Laenkean *ŋ̊g<rǽp>z-, from the Proto-Laenkean root *PL. *ᵑgæz-(to invoke).
From Middle Radestrian aurahhașș, from Old Radestrian awrahhašro, from Proto-Radic *aǧrahhašur, from *aǧrahs(equal) + *hāšur(night), equivalent to oraiș + háșe.
From Middle Radestrian ostárs, from Old Radestrian awstārss, from Proto-Radic *aǧstārhs(sprout), from Proto-Hirdic *ghəstáḡərṯəs, from Proto-Laenkean *gʱa-sta<gar>t-as, from the Proto-Laenkean root *stat-(to grow).
From Middle Radestrian autair, from Old Radestrian avtair, from Proto-Radic *abtawir, from Proto-Hirdic *aḇtákhwis, from Proto-Laenkean *m̥btʼ-ń̥k(ʰ)we-, from the Proto-Laenkean root *ᵐbotʼ-(solid, firm).
From Middle Radestrian otú, from Old Radestrian avtŭw, from Proto-Radic *abtıg, *awıg, from Proto-Hirdic *aḇtɯ́ḡ, from Proto-Laenkean *⁂m̥btʼɯ́g, from the Proto-Laenkean root *ᵐbæj(n)-(interrogative).