An indespensible tool for students and scholars of biblical Hebrew is a good lexicon (a fancy title for a dictionary).While beginning readers will want a basic lexicon by their side while working through a passage, for in-depth research you will want to consult a multi-volume advanced dictionary.
One of the most affordable Hebrew-English dictionaries available is:
By far the best traditional Hebrew lexicon currently available is:
This work has the advantage of being up to date and easy to use as entries are arranged alphabetically. Unfortunately, its price puts it out of the reach of most students and scholars (and hence, I did not even bother to include a link to purchase it!). A more affordable edition which I highly recommend is available as:
An older abridgment of KB is
Holladay's volume is based upon the 2nd and 3rd editions (only two-thirds of KB3 was completed at that time), and like KB entries are arranged alphabetically, though etymologies and cognate languages are omitted.
Finally, a reference lexicon that is appearing slowly is:
This is the first Hebrew dictionary that is based on modern linguistic principles and that takes into consideration all available non-Biblical Hebrew texts up to ca. 200 CE, including the Dead Sea Scrolls. The scope and cost of this dictionary (a projected 8 volumes), however, also puts it beyond the means of most students.