ballpark figure of speech

Reader's Digest 5月号のコラム記事 "Ballpark Figure of Speech" から引用します。
Most of us prefer to say someone "passed away" rather than "died," or got "let go" instead of "fired." But while more than 9 in 10 Americans use euphemisms such as these, nearly 3 in 5 admit to having used one without really knowing what it meant. Among the most confusing:
"Economical" (cheap)
"For the birds" (unimportant)
"Frumpy" (unattractive)
"Indisposed" (in the restroom)
"Monday morning quarterback" (someone who criticizes after the event)
"Up to scratch" (good enough)

"ballpark figure" は普通数値とか量についての概算を言うのですが、この記事のタイトルでは "Figure of Speech" を指していますね。
ここでの "Figure of Speech" は "euphemism" を指しているのは文脈からも分かりますが、 "figure of speech" の説明を辞書で見ます。

・Oxford English Dictionary: a word or phrase used in a different way from its usual meaning in order to create a particular mental picture or effect: When we talk about ‘selfish’ genes it is just a figure of speech.
・Collins Dictionary: A figure of speech is an expression or word that is used with a metaphorical rather than a literal meaning.: Of course I'm not. It was just a figure of speech.
・Cambridge English Dictionary: an expression that uses words to mean something different from their ordinary meaning: "Break a leg" is a figure of speech, meaning "good luck".