If you want an online dictionary then "spoken Sanskrit" offers a free dictionary for all. (spokensanskrit.org) It is the best dictionary for beginners. This dictionary offers Sanskrit to English or English to Sanskrit search as well as transliteration. Apart from that, you can refer to V. S. Apte's online dictionary V.S.Apte's Sanskrit Dictionary.
If you want a hard copy dictionary format then you can buy V.S.Apate Sanskrit dictionary.
If you want an online dictionary then "spoken Sanskrit" offers a free dictionary for all. (spokensanskrit.org) It is the best dictionary for beginners. This dictionary offers Sanskrit to English or English to Sanskrit search as well as transliteration. Apart from that, you can refer to V. S. Apte's online dictionary V.S.Apte's Sanskrit Dictionary.