SEO definition

SEO is a short form of Search Engine Optimization.
                SEO is a process of enlisting or re indexing a website or a web page into search engine for targeted keywords, get volume and quality traffic.

                Search engine optimization (SEO) is the process of affecting the visibility of a website or a web page in a search engine's "natural" or un-paid ("organic") search results.

                Search engine optimization is a methodology of strategies, techniques and tactics used to increase the amount of visitors to awebsite by obtaining a high-ranking placement in the search results page of a search engine (SERP) -- including Google, Bing, Yahoo and other search engines.

                SEO Short for search engine optimization, the process of increasing the number of visitors to a Web site by achieving high rank in the search results of a search engine

1. SEO is the ongoing process of uncovering and discovering non-branded keywords that are driving organic search traffic and conversions, then publishing content optimized for those keywords.
2. SEO is the process of producing optimized content that is discoverable by the target audience as they progress through the buying cycle.
3. SEO is about a prospect discovering a brand's content and web presence through search and social, and the owner of that content being able to understand who consumed the content and the impact of the content across the organization.
4. SEO is the outcome of a content marketing strategy that makes use of highly converting keywords that your target audience is searching on.
5. SEO is the process of enhancing the visibility of a brand's web presence in organic search.

Source links:

http://en.wikipedia.org/wiki/Search_engine_optimization

http://www.webopedia.com/TERM/S/SEO.html

http://moz.com/blog/smwc-and-other-essential-seo-jargon

http://searchenginewatch.com/article/2288392/Time-for-a-New-Definition-of-SEO