JWLuiza
Black Belt
Please consider buying this book:
http://www.24fightingchickens.com/kata/
I got the following information from this book:
It probably means something closer to: To extract from a fortress, or rescue. The first character in Bassai is "batsu" or "nuki" and means to extract or draw out. The next character, fusagu or sai means close, obstruct, etc. However, nowhere in any chinese dictionary for the pictograms does the word penetrate appear.
Rob Redmond, the author, lived in Japan for three years and has a great Blog at www.24fightingchickens. The book also has step by step instructions for the shotokan versions of these forms.