Is there a word to describe someone who rarely or almost never gets upset/angry? The words that first came to my mind were non-confrontational and stoic, and though they relate, they are not exactly what I'm looking for. The word I'm trying to find describes a person that not only possesses the qualities of being non-confrontational and stoic, but he basically doesn't get upset over anything whatsoever even the most upsetting situations imaginable. He is generally a pretty happy, calm and collected individual. Is there such a word?
Unflappable describes someone who remains composed in the face of adversity or scandal, "impossible to fluster."
Stoic has the same meaning, but often implies indifference to pleasure as well as adversity.
The state you describe is equanimity:
noun [mass noun]
calmness and composure, especially in a difficult situation:
she accepted both the good and the bad with equanimity
The adjective is equanimous.
calm and composed.
However it would not be the best choice in normal use. Google Ngram
How about placid? From Merriam-Webster.com: Definition of PLACID:
serenely free of interruption or disturbance
a person who believes that this world is the best of all possible worlds or that good must ultimately prevail over evil.
Cool customer, e.g. someone who stays calm and does not show their emotions, even in a difficult situation (https://dictionary.cambridge.org/dictionary/english/cool-customer).
The lack of a conspicuous example makes this incrementally more difficult to answer. If you perhaps want some generic adjectival synonyms for "happy", my suggestions are amiable, blithe, and the always-applicable mild. Another (presumably) acceptable term that could be used in a similar manner is sweet-tempered. On a related note, you'd most likely be able to simply state that the person has a gentle disposition.
Additionally, if you'd appreciate a word that more specifically denotes optimism in regard to (and especially in) a difficult or severe situation, consider sanguine.
having or displaying a friendly and pleasant manner.
showing a casual and cheerful indifference considered to be callous or improper.
- happy or joyous.
2. gentle and not easily provoked.
not easily irritated or made angry.
optimistic or positive, especially in an apparently bad or difficult situation.
I sincerely hope that this assists you. If anybody has an inquiry about the content of this post, please feel free to leave a comment about it -- I will respond as soon as I am able to.