for twice a day
If you can read the illegible prescription the doctor gave you, and it says "2 capsules b.i.d," it translates to 2 capsules, given twice a day. It's latin for "bis in die."
Now, if it was t.i.d, it'd be three times a day(ter in die). After that it's q.i.d for four times a day(quater in die). q.o.d is every other day.
Thanks to Dann for memorizing so much useful latin.