Whatever has 6 different meanings across 4 categories:
Something whose exact kind or nature is unimportant; a thingy.
"Just grab whatever you find on the counter for lunch since I don't really care what we eat today."
In plain English: Whatever is an attitude of not caring about something because it doesn't matter to you.
"He didn't care what I said, so he just shrugged and muttered whatever."
one or some or every or all without specification
"give me any peaches you don't want"
"not any milk is left"
"any child would know that"
"pick any card"
"any day now"
"cars can be rented at almost any airport"
"at twilight or any other time"
"beyond any doubt"
"need any help we can get"
"give me whatever peaches you don't want"
"no milk whatsoever is left"
Unexceptional or unimportant; blah.
"The movie was whatever, so we decided to go home early."
In plain English: Whatever describes something that is unimportant or doesn't matter at all.
"She wore whatever skirt she found in her closet."
Usage: Use whatever as an adjective to describe something ordinary, mediocre, or lacking in quality when you want to express indifference or disappointment. This informal term often replaces more specific adjectives like average or bland to dismiss the subject's significance casually.
no matter what; for any
"Whatever you choose to eat, I will be happy as long as we share it together."
No matter what; for any
"Whatever you decide to do, I will support your choice no matter how difficult it might be."
A holophrastic expression used discourteously to indicate that the speaker does not consider the matter worthy of further discussion.
"Whatever, I'm done talking about your messy room and leaving you to deal with it yourself."
Whatever comes from Middle English and is formed by combining the words "what" and "ever." It originally functioned as an indefinite pronoun before evolving into its modern usage.