Vocab Floating World p181-206

1.bewilderment(191)
Indeed, Suichi also expressed his bewilderment when I read him Noriko's letter.(191)
Bewilderment is feeling of being confusion. It's means when Setsuko read Noriko's letter to Suichi, he also expressed his confusion about Ono's behavior.

2.slip up(191)
It was you who suggested I take "precautionary steps" so that we didn't slip up with the Saitos as we did with Miyakes.(191)
Slip up means make small or unimportant mistake. Here means because Setsuko give Ono suggested to take precautionary steps and Ono think he did, that why they didn't make same mistake with Miyakes.

3.prevalence(192)
Mr Naguchi's songs came to have enormous prevalence at every level of the war effort.(192)
Prevalence means generally,pop. This sentence means Setsuko think Mr Naguchi's songs have very big and generally effect at war.

4.disillusioned(199)
You were very disillusioned  then.(199)
Disillusioned means disappointed to something and no any hope. Here means Matsuda think Ono were very disappointed about painting.

5.uneasy(200)
The smell of burning still makes me uneasy.(200) 
Uneasy means feel uncomfortable and anxious. Here means when Ono smell of burning he still feels uncomfortable and anxious.

6.convictions(202)
But this is surely preferable to never putting one's convictions to the test.(202)
Convictions means strong and an unshakable belief. Here means never putting one's strong belief  to the test is better.