AbiWord is a lightweight word processor. Includes support for tables, images, equations, English language thesaurus, link-grammar, spell check, mail merge, etc. Drawn from a cross-platform code base, the program can open and save to a wide variety of file types including Word (.doc and .docx files), OpenOffice, and many more. Online help documention can be found here.
AbiWord Portable is a wrapper from PortableApps.com. 2.9.4 is the last Windows version, which AbiSource released in 2012.
