Latin Dictionary: How to Actually Look a Word Up

A Latin dictionary is not hard to read. It is hard to enter, because the word you are holding is almost never the word the dictionary filed it under. You met regibus; the dictionary knows only rex. You met amaverunt; the dictionary knows only amo. The gap between the form on the page and the form in the book is the single thing that makes looking Latin up feel like a fight, and it is entirely learnable. Here is the map.

Everything lives under the lemma

A dictionary cannot list every form of every word - Latin has too many. A single verb has well over a hundred inflected forms, a noun a dozen. So the dictionary picks one form per word, the lemma or citation form, and files everything under it:

• Nouns under the nominative singular: rex, terra, corpus.
• Adjectives under the masculine nominative singular: magnus, bonus, fortis.
• Verbs under the first-person singular present: amo (I love), not the infinitive you might expect.

So the reading skill and the look-up skill are the same skill in reverse. Reading, you go from rex to regibus. Looking up, you go from regibus back to rex. And the return journey is the harder one, because the ending you can see (-ibus) tells you the case but not the stem, and the stem is what the entry is alphabetised on.

The two forms a noun is cited with

Open any entry and a noun comes with a passenger:

rex, regis - king

The second word is the genitive singular, and it is not decoration. It reveals the stem - reg- - which the nominative rex hides completely, and it identifies which of the five declension families the noun belongs to. Without it you cannot build regem, regibus or any other form. This is the whole reason Latin dictionaries list every noun twice, and the reason "learn the genitive with the noun" is the most repeated instruction in Latin teaching. A noun learned without its genitive is a noun you can recognise and cannot decline.

Principal parts: why a verb entry has four forms

A verb is cited with even more, because a verb hides even more:

amo, amare, amavi, amatum - to love

These are the principal parts, and each unlocks a different chunk of the conjugation:

• amo (first-person present) and amare (infinitive) give you the whole present system - present, imperfect, future.
• amavi (first-person perfect) gives you the entire perfect system. You could not guess it: regular -avi here, but video gives vidi, capio gives cepi, fero gives tuli.
• amatum (the supine) gives you the perfect participle and the passives.

The point of listing them is that the irregular verbs are irregular precisely here and nowhere else. Fero, ferre, tuli, latum conjugates like an ordinary verb once you have those four forms, and is unguessable without them. When you meet tulerunt in a text and go looking, you will not find it under T - it lives under fero, because tuli is that verb's perfect. That leap, from a form to a lemma that shares no letters with it, is called suppletion, and it is the thing a parser exists to rescue you from.

The dictionaries worth knowing

Lewis and Short (formally A Latin Dictionary, 1879) is the standard one-volume dictionary of classical Latin, and it is free. You will find it on Logeion and the Perseus Digital Library, both of which do the return journey for you: paste regibus and they parse it back to rex and tell you it is dative or ablative plural. Use the parser without shame - reading fluency comes from reading, not from flipping pages.

The Oxford Latin Dictionary (the OLD) is more authoritative and more current in its scholarship, strictly classical, and not free. It is the one to reach for when Lewis and Short leaves you unsure.

The DMLBS - the Dictionary of Medieval Latin from British Sources - is the reference for the Latin actually written in Britain between 540 and 1600, which drifted a long way from Cicero. If you are reading charters, chronicles or scholastic philosophy rather than Virgil, classical dictionaries will quietly fail you and this is where you go. It, too, is now free online.

Why frequency-first beats dictionary-diving

Here is the honest part. The dictionary is a reference, not a course, and learning vocabulary by looking each word up as you hit it is one of the slowest methods there is. You do the hard lemma-identification work cold, thousands of times, on words you may never see again.

The alternative is to meet your words in order of how often they occur, each one arriving with its genitive or its principal parts already attached, so the identification is done for you the first time and reinforced every time after. That is exactly how our Latin course is built: the commonest words first, each with its own word page carrying the principal parts, the stem, example sentences and audio. Learn fero deliberately once and tulerunt stops being a locked door forever.

Dictionary-diving has its place - you will always meet the rare word that no course covers, and then Logeion is your friend. But do not confuse the reference with the road. The reference is where you settle an argument about a word; the road is learning the words in the order the language uses them.

Cross-references

• Latin declensions - why every noun is cited with its genitive, in full.
• How to learn Latin - the frequency-first method the dictionary cannot replace.
• Is Latin hard to learn? - the honest reckoning, look-ups included.
• Latin example sentences - real forms to practise the return journey on.
• The Latin course - where the words arrive in order, with their principal parts attached.