I am extracting keywords from webpage using this resource. It works fine but some words are getting malformed. The word "memory" is extracted as "memori" and "article" is extracted as "articl". There are many other keywords with similar behaviour. Here is a list(var_dump($uniqueKeywords)) of some keywords extracted from this URL as an argument to the function.
P.S.: I am not stripping off the numbers.
The words are transformed using a Stemming algorithm. Stemming allows different forms of a word to match, e.g. "memory" and "memories" both transform to "memori". Note that the stemmed words usually aren't actual words, but should only be use for comparison.
If you don't want this behaviour, skip the 'Stem the words' section of the tutorial.