The adjective tough is good for describing hard times. If you just got mugged, lost your job, got the flu, and broke your toe, you're having a really tough week.
Tough means "strong, hard, unbending," and you can use it to describe many different things, like a tough exam, or a tough piece of beef jerky, or a tough day that you just want to be over. If a judge punishes criminals harshly to set examples, she's "tough on crime." We call people toughs if they seem likely to beat you up. Tough things are made to withstand a beating, like the tires on your mountain bike. Pronounce: TUFF.