Before 1900 a noun modifying a noun had to be joined to it by a hyphen, as in dinner-table or marriage-vow.  But today we drop the hyphen and either combine the two words (as in bathroom) or keep them separate (as in living room).  I'm seldom sure whether to combine or separate.  The nouns are combined in “flashlight” but not in "light bulb."  They're combined in "bluebird" but not in "blue jay."  I'm glad for the computer's spell checker.  Or is it "spellchecker"? 

We have continued to use a hyphen in compound adjectives such as in “dinner-table conversation” and “computer-based solution”—until recently, that is.  Now it’s become “dinner table conversation” and “computer based solution.”  This can result in confusing sentences such as “Tonight's other celestial targets include the crowd pleasing planet Saturn.” [reference]  Is the crowd a celestial target?  Why does the crowd please Saturn?  After a second reading the meaning is clear, but I mourn the demise of the hyphen in compound adjectives.  

 Still-Hyphenated Compound Nouns