Below are possible answers for the crossword clue 86 is a high one.
AGE
how long something has existed; "it was replaced because of its age"
grow old or older; "She aged gracefully"; "we age every day--what a depressing thought!"; "Young men senesce"
a time of life (usually defined in years) at which some particular qualification or power arises; "she was now of school age"; "tall for his eld"
begin to seem older; get older; "The death of his wife caused him to age fast"
a late time of life; "old age is not for sissies"; "he's showing his years"; "age hasn't slowed him down at all"; "a beard white with eld"; "on the brink of geezerhood"
make older; "The death of his child aged him tremendously"
a prolonged period of time; "we've known each other for ages"; "I haven't been there for years and years"
an era of history having some distinctive feature; "we live in a litigious age"
epoch/era
PROOF
make resistant (to harm); "proof the materials against shrinking in the dryer"
activate by mixing with water and sometimes sugar or milk; "proof yeast"
read for errors; "I should proofread my manuscripts"
knead to reach proper lightness; "proof dough"
make or take a proof of, such as a photographic negative, an etching, or typeset
(used in combination or as a suffix) able to withstand; "temptation-proof"; "childproof locks"
the act of validating; finding or testing the truth of something
a trial photographic print from a negative
any factual evidence that helps to establish the truth of something; "if you have any proof for what you say, now is the time to produce it"
(printing) an impression made to check for errors
a formal series of statements showing that if one thing is true something else necessarily follows from it
a measure of alcoholic strength expressed as an integer
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