Pravin -
You definitely CAN... but that's not always the best idea. We do car dealer websites, and we feed our dealers' inventories out to hundreds of online classified sites. Many of our dealers also use eBay motors. Our system allows them to either write a single description that goes to every property, or separate descriptions for website, eBay, and classifieds.
You should be able to do the same thing with your site. You should always have a bit more detail and depth on your own website, but if your system doesn't allow for you to do so, you'll probably still be ok. The search engines are smart enough to realize that the different online stores and classified sites are all selling the same product (and won't assign a dupe content penalty).
Remember - you should always look at your website and create content/descriptions that your customers (and potential customers) will find the most useful and relevant. Write for people, not for search engines. Plus, you've got different audiences on the other sales platforms, so unique descriptions might help with conversions, based on the audience you're trying to reach. BUT, if you're not able to, you should be ok with using the same description across the board.
