Dictionaries and Etymology
Sanskrit Reference Books and Online References
An excellent ONLINE way to look up words is here.
The following are the same dictionary, but with different quality printing and binding.
BOTH OF THEM REQUIRE YOU TO BE ABLE TO READ THE SANSKRIT DEVANAGARI SCRIPT.
Apte, Vaman Shivaram. The Practical Sanskrit-English Dictionary, Revised and Enlarged Edition,Kyoto, Japan: Rinsen Book Company, 1998. HIgh quality binding and printing, small and thick. This is my favorite dictionary, but it is difficult to find. (ISBN: 4-653-00038-7)
Apte, Vaman Shivram. The Practical Sanskrit-English Dictionary, Nataraj Edition, Springfield,Virginia: Nataraj Books, 2007. Very good binding and printing, larger print, heavy. (ISBN: 1-881338-61-4). Available at Nataraj Books.
The dictionary below is the standard academic dictionary. YOU DO NOT NEED TO READ THE SCRIPT FOR THIS ONE.
Monier-Williams, Sir Monier. A Sanskrit-English Dictionary, New Delhi, India: Motilal Banarsidass Publishers, New Enlarged edition, 1899. This edition is very large and heavy, but does show both the Sanskrit Devanagari script as well as the transliteration. It does state in the introduction however, that he was a Christian missionary and was commited to converting Hindus to Christians, even going so far as attempting to translate the Christian bible into Sanskrit for that purpose.
Apte, Vaman Shivram. The Student’s English-Sanskrit Dictionary, New Delhi, India: Motilal Banarsidass Publishers, 3rd edition, 1920. NEED TO BE ABLE TO READ THE SANSKRIT DEVANAGARI SCRIPT. (ISBN: hardback 81-208-0299-3, paperback 81-208-0300-0)
Etymology (Words Related to Sanskrit Roots)
Whitney, William Dwight. The Roots, Verb Forms and Primary Derivatives of the Sanskrit Language. New Delhi, India: Motilal Banarsidass Publishers,2006. (ISBN 978-8120804852). This will show all the words in Sanskrit that are made from each Sanskrit root.