My favorite Torah dictionary (if it can be called that) is “Erchei Hakodesh” by Rabbi Avraham Nachman Simcha Weitzhandler.
Find it on Otzar Vachochma here.
From the blurb:
ערכי הקודש והם ערכים וענינים נפלאים נאמנים ונחמדים בנויים ומיוסדים על ערכי ומשפטי לשון הקודש והמסתעף ממנה
ממקור קדוש יהלכון מזוקקים שבעתיים מדברי חז”ל חכמי הגמרא ראשונים ואחרונים הנערכים לכל שוחרי משפט דת ודין תורתנו הקדושה
Here’s a partial image:
(Jastrow (available online on Sefaria and other places) is strictly limited to Chazal.)
What’s so great about it is that each entry simply copies some original source (Rashi, Radak, gemara, Medrash, etc.) referring to the term in question or uses the Malbim and similar works which are hard to read in the original, all this as opposed to the painful paraphrasing in the secular dictionaries (and not always done accurately, since their authors are generally (though not always) Torah ignoramuses, or worse).
Of course, Erchei Hakodesh omits “modern Hebrew” words or new definitions for older words since it’s about “Lashon Hakodesh”, unlike secular dictionaries which place the modern usage first, and the “rarer”, rabbinic/Talmudic one later in the list, if at all. And while it may be strange to see full quotations, and some of it may occasionally be unneeded, it’s ultimately a “Derech aruka shehi ketzara”. Sometimes Erchei Hakodesh will have several consecutive entries for the same word, each giving a different insight (not necessarily contradictory). The work is thought through; he wisely won’t quote some famous Rashi if it doesn’t give the full picture, but find some Ibn Ezra on Tehillim which does.
And it’s not “scientific”.
It has things you wouldn’t expect, but upon reflection, well… like this:
On the downside, there are three overlapping volumes. The alphabetical order is imperfect (the first letter of each word is kept in order, but the alphabetical order with the following letters is inconsistent – Think Shem Hagedolim).
Sure, it takes getting used to, and you may have to search a lot more, but it has no competitors I know of for its unique model.