Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
sum-mŏlestus (subm-), a, um, adj., somewhat troublesome or vexatious (very rare): illud est mihi submolestum, quod, etc., Cic. Att. 16, 4, 4.
Adv.: summŏle-stē, with some vexation: aliquid ferre, Cic. Att. 5, 21, 1.