Wendy, you said it just fine, silly!
Nicole, when DS was younger, BT at X:XX meant asleep by then. Now that he's older and doesn't get OT so easily, it's more flexible and depending on the day we've had, it can mean when he's laid down or when we want him to be asleep. Temperament plays a lot into this as well, as does how easily your LO handles a OT/OS if they're not asleep by a certain time.
When giving advice on the boards, however, I will say bedtime in the context of "Needs to be asleep," and let the parents figure out what needs to happen prior to make it happen (offering advice there, too, if need be).