A classic Greek lexicon useful for every theology student. Note that Thayer was a universalist, so be careful with any word dealing with salvation, and also the Trinity (his definition of “Christ” would seem to doubt Jesus’ deity). Basically the majority of his word definitions are from standard usage in the Greek NT and classical literature, so in theologically charged words, be careful.
Strong Diccionario Griego y Hebreo al Español
Mounce Concise Greek-English Dictionary of the New Testament
Hebrew/Greek Synonym Dictionary is a dictionary module showing the Hebrew to English or Greek to English root words.