Arioso, and Aria, solo musical number in the Opera. It is usually less arias. If Aria is a generalization, reasoning, then Arioso - rather a direct response to something only that the event occurred. For example, Lensky's Arioso "In Your house".
Happened irreparable. Lensky has caused Onegin to a duel. Broken his dreams of happiness with Olga. Arioso sounds like a heartfelt remembrance of the past, serene, joyful days spent in the Larins ' house.
Lensky's Arioso "In your house" from the Opera of P. I. Tchaikovsky's "Eugene Onegin"
(sings Sergei Lemeshev)