Using semantically related words on your web pages can help with your SEO marketing efforts. Some say that Google uses a form of LSI or Latent Semantic Indexing to analyse the context of the page copy against related words. This is so spammy websites that just ramble a lot of nonsense or turbo blog can’t just keep updating their web pages with keywords peppered in. If they fail to reference semantic lay related keywords and phrases, they run risk of being semantically distanced from the keyword that they have optimised for. This method has evolved some way since the early search engine algorithms that would simply calculate the keyword density!
But how can you tell if your webpage is semantically relevant?
Firstly, don’t assume that by inserting synonyms beside your keywords will help! Synonyms actually are considered by the search engines to be identical to the keyword and can cause keyword density to skyrocket! This could ultimately lead to lower rankings. The way the search engines calculate the relevancy is by searching the breadth of the vocabulary and making contextual relationships between common subject materials.
In my honest opinion, I think that if you are concentrating on writing good helpful content then your website should be semantically related anyway!
Also, anchor links should be varied (semantically if possible) otherwise over optimisation can hold back rankings!