once-in-a-lifetime

The current energy and industrial boom, according to Siemens President Joe Kaeser, “is a once-in-a-lifetime moment.”

For people who love history, this is a once-in-a-lifetime, once-in-history resource.

Not that this once-in-a-lifetime spectacle is likely to come to pass.

Investors will view the Facebook IPO as a once-in-a-lifetime event.

Charity auction site charitybuzz to host a star-studded line-up of once-in-a-lifetime experiences.