Can DVD's be played on a laserdisc player?

Assuming you know that LaserDiscs are not only a different format, but a different size than DVDs, The answer is Some.

Their are Combination players that can play several formats. The DVL Series of LaserDisc players, manufactured by Pioneer can play LaserDiscs, DVDs, CDs and CD videos.

I suggest getting a DVL-919 player. You can still purchase this model brand new on pioneer's web site: http://www.pioneerelectronics.com/PUSA/Products/HomeEntertainment/Blu-rayDisc+DVD/DVD+LDPlayers/DVL-919