Give and bestow refer to presenting something voluntarily to someone, without expecting anything in return. This is the primary definition of give, which we use with “gift” and “present,” or the specific item given (I’m giving her a bike for her birthday). Bestow is very similar to give in the action it denotes, but it is generally used for intangible or unspecified treasures that can’t be bought, such as blessings, honor, grace, gifts, wealth, title, or authority, which are bestowed on or upon someone, often by someone in a high position–God is frequently the subject of bestow. Bestow is an elevated, formal term which can have a ceremonial feel of past eras, but you will encounter it adding nuance to more ordinary acts (bestowed a kiss on his cheek, bestowed a radiant smile upon her guests).
Letter and missive refer to a written communication addressed to one or more people normally sent by mail or email. Letter is the general term and is used particularly when the message bears the conventional format of a hand- or typewritten letter, rather than being an email or text. Missive is a rather formal, less familiar synonym for letter, often used for an official or public communication (the CEO’s missive to shareholders), but it can be used for any message or announcement that is directed towards an individual or group (the latest in a string of Twitter missives from the Governor). It’s not entirely clear why missives are more often said to be “fired off” than letters are, but its shared root with “missile” (miss- meaning “send”) may have something to do with that.
Corrupt and venal apply to a person or act, especially in public office, whose motives are mercenary and self-interested, without regard for honor, right, or justice. Corrupt, the much more familiar term, is used of institutions (corrupt government, corrupt system) as well as individuals (corrupt politicians), whose morals have been eroded by temptations of power, especially bribery. Venal, which originally meant “for sale,” tends to be used of individuals and their actions (venal politician, venal motive). It often implies a more repulsive, personal quality, one that is shamelessly open to bribery, willing to sell patronage, and thoroughly debased before they entered office.