The CHO group in an aldehyde is called the aldehyde group.
See also ketone.
OCHEMPAL IS NOW IN THE FORM OF A BOOK
Title: The Elements of Organic Chemistry; Subtitle: A Compendium of Terminology, Definitions, and Concepts for the Beginner.
Available at Amazon or the publisher’s website: http://linusbooks.com/?wpsc-product=the-elements-of-organic-chemistry
The book contains everything on OChemPal except some recent additions, a few biochemical terms, and the Mastery Check feature. So, if you prefer reading a book to reading a screen, the book is for you.