Picture a sentence that never finishes: 'if the rain stops...', 'if they confirm...', 'if the signal holds...'. iffy is if with -y on the end, and everything it describes is still hanging on that if. Nothing has landed yet, so you hold off before you book, pay or eat it.
可以想成一句話還卡在「如果…的話」這裡。iffy 就是 if 加上 -y。如果雨停、如果對方確認、如果訊號有進來——只要那個 if 還在，事情就還吊著，沒有落地。所以聽到 iffy，通常的反應是先不要下訂、先不要決定、先不要吃。
From the word’s history
iffy is simply if plus -y, which is why every use still has a condition hanging inside it.
iffy 就是 if（如果）加上 -y。造字方式這麼直接，所以它的每個用法裡都還留著一個沒有解決的「如果」。
Wiktionary etymology supplied in this packet (source_ref kaikki:3f6f69a190036ae4:602268885): "From if + -y."
登入就可以看每一支怎麼連回核心畫面。