greatly; fully; to a high degree; (when used after 不 bù) not very; not often

(bound form) to fail to meet a goal or desire; to be disappointed (as in 失望 shī​wàng or 失意 shī​yì)

Used before a verb to form a noun-like phrase representing the object of the action, meaning "that which" or "what".

to hope; to expect; to look forward to