Of all the dictionaries out there, do any indicate the frequency of words (e.g. from very frequent to very rare)?
My problem is that sometimes I learn a random page in my Latin dictionary but I don't know if the words there are rare words for which there is a more common equivalent.
You'll see it in regular dictionaries. Lewis and Short will often say whether something is "rare" or "very frequent" and sometimes will even indicate the period in which the frequency changes. It does it not only for words, but also definitions.
For example, let's take the word scelero:
I.perf., ātum, 1, v. a. id., to pollute, defile, contaminate, desecrate (in the verb. finit. rare, and only poet.; “syn.: temero, polluo)
You'll see that not only is the finite form of the verb rare, it is only found in poetry. You wouldn't use it (for whatever reason) if you're construction and oration or writing a history. Additionally, it provides synonyms so you know which words to choose instead.
Or with sanguineus:
I. Lit., of blood, consisting of blood, bloody, blood- (class.; a favorite word of the Aug. poets)...
II. Transf., blood-colored, blood-red (poet. and in postAug. prose): “jubae
It chiefly relates to blood (including some metaphorical uses, like in bloodthirsty) in classical literature, but in poetry and in post-Augustan (so "Silver Age" and later) prose, it also denotes the color red.
A related word, sanguinarius, shows additional notes:
I.of or belonging to blood, blood-, I. Lit.: herba, an herb that stanches blood, the Gr. πολύγονον, Col. 7, 5, 19; “also called sanguinaria alone,” Plin. 27, 12, 91, § 113, and sanguinalis herba, Col. 6, 12 fin.; Cels. 2, 33; 3, 22 fin.: latus sanguinare, covered with blood, Vulg. Ecclus. 42, 5.— II. Trop., blood-thirsty, bloody, sanguinary (rare but class.): “juventus,” Cic. Att. 2, 7, 3: “Claudius (with saevus),” Suet. Claud. 34: “bella (with cruenta),” Just. 29, 3, 3: “sententiae,” Plin. Ep. 4, 22, 6: “illud responsum,” Plin. 19, 8, 53, § 169.
So there you'll see two definitions contrasted. Sanguinarius usually denotes something physically related to blood. Metaphorical usages is relatively rare, but since Cicero uses it once in this way, it is "permitted" if you want to compose Latin in good, Classical style.
Lewis and Short is inexact, and of course much work has been done on frequency since, such as automatic corpora scanning. A good resource in my opinion is the Dickinson College Commentaries website, which has a section on "core vocabulary," and it includes the rank assigned to each word.
You'll have to be careful, though, since some websites which show frequency don't group inflected words, so alii will sit alongside alia in the list. (See this one for example.)
The dictionary aggregator Logeion is the go-to place for this - on the right it not only shows the word's exact frequency, but its most common collocations as well. In this case, the spelling VAS represents two different lemmas - vas 'human bail' & vas2 'vessel', and Logeion gives separate collocations for each of them, one under the other; however, only vas2 is given frequency information (hopefully this will be improved upon).
Generally you can judge the frequency of a word by the number of citations in L&S and the relative length of its entry - although sometimes they just give a list of citations while barely quoting any, as with doctor, which may create a false impression of its being infrequent.
In the Frequency section you can click on the names of authors to see all occurrences. Sometimes it will search for the wrong of the two lemmas - for example Tibullus never had the occasion to use the word ānus 'butt-ring'. To search for the other lemma, anus 'old woman, gramma', change word=lemma:anus for word=lemma:anus2 in the address bar to get the following list.
Apart from that, the basic way to check word frequency is searching a corpus, usually PHI - but if the word has homographs (which most Latin words do), it's up to you to “lemmatise” it.
