factoid

Reader's Digest Sept Issueの記事 'Words That Mean the Opposite of What They Sound Like' で次の五つの単語を取り上げていました。
Enervated/Factoid/Inflammable/Noisome/Nonplussed
確かに "Enervated" と "Inflammable" は反対の意味を連想してしまいそうです。
"Factoid" は1/11/2017に "juicy factoid" として取り上げました。
"Nonplussed" は8/6/2009に "nonpluss" を取り上げています。
ここでは記事からFactoidの説明だけを引用します。
FACTOID People think it means "a fun, trivial fact." But it originally meant "a fun, false fact." Coined by Norman Miler in 1973 to describe "facts" invented by reporters, this word can (confusingly) describe both true and false information. But for Mailer's intended meaning, look to the suffix: -oid. If a humanoid resembles a human (but isn't one), it follows that a factoid resembles a fact--but isn't one.