fossil group
n.— «All that dark matter makes astronomers think that NGC 1132 grew up through the mergers of many smaller galaxies in an entire group, drawn in by the dark matter. That’s why the galaxy is sometimes called a “fossil group.” However, they can’t rule out a scenario in which NGC 1132 was born as a full-fledged giant—perhaps under conditions that somehow suppressed the formation of lesser galaxies.» —“See A Dark-matter Magnet” by Alan Boyle MSNBC: Cosmic Log Feb. 5, 2008. (source: Double-Tongued Dictionary)
Further reading
If you speak a second or third language, you may remember the first time you dreamed in that new tongue. But does this milestone mean you’re actually fluent? And a couple’s dispute over the word regret: Say you wish you’d been able...
Mary Beth in Greenville, South Carolina, wonders: Why do we say four-oh-nine for the number 409 instead of four-zero-nine or four-aught-nine? What are the rules for saying either zero or oh or aught or ought to indicate that arithmetical symbol...