Condolence, Regret, Sympathy, Lament
noun, verbal noun, の adjective
Grieve for a pathetic situation by offering your condolences. Showing regret is the best way to handle it.
あいとう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
哀悼の意を表して、黙祷しました。
I expressed my condolences and prayed silently.