"Strong yen" refers to a situation where the Japanese currency, the yen, is getting stronger compared to other currencies. This means that it takes more of a foreign currency to buy one unit of the yen. Full definition
The USD is currently up 0.0006 against the euro, trading at 1.3339, after peaking at 1.3351 earlier in the day, however it has slid against a particularly strong yen. (financialtrading.com)
That's what foreigners call a mix of reforms that Japan's Prime Minister Shinzo Abe hopes will dig his country out of 15 years of deflation and stagnation, but that some have painted as a stealth attempt to get the perennially strong yen to depreciate and thus artificially boost Japanese exports. (macleans.ca)
A decline in new export orders in Japan as the stronger yen began to affect exports, along with sluggish household spending in the US, contributed to those fears. (cumber.com)