The following dictionaries and lexicons are available either in print or online.
Print (Brill, 2015): The Brill Dictionary of Ancient Greek is the English translation of Franco Montanari’s Vocabolario della Lingua Greca. With an established reputation as the most important modern dictionary for Ancient Greek, it brings together 140,000 headwords taken from the literature, papyri, inscriptions and other sources of the archaic period up to the 6th Century CE, and occasionally beyond. This dictionary is an invaluable companion for the study of Classics and Ancient Greek, for beginning students and advanced scholars alike.
Print, 2 vols.; by Robert Beekes (Brill, 2010): This dictionary is a treasure trove covering 2000 years of Ancient Greek: from Mycenaean via Homer and the classical period to lexicographers, such as Hesychius (5th century A.D.). It consists of 7500 entries with thoroughly revised etymologies. Each entry gives clear information about the origin of the Greek word and its first date of attestation. It further provides all etymologically relevant variants, dialectal forms, derivatives, compounds, and bibliographical references.
Print, 9th ed. (Clarendon, 1996): Liddell and Scott's Greek-English Lexicon (also known as Liddell-Scott-Jones, or LSJ) is the most comprehensive and up-to-date Ancient Greek dictionary, used by every student of Ancient Greek in the English-speaking world. The main dictionary covers every surviving Ancient Greek author and text discovered up to 1940, from the Pre-Classical Greek of the 11C - 8C BC (for example Homer and Hesiod), through Classical Greek (7C - 5C BC) to the Hellenistic Period, including the Greek Old and New Testaments. Entries include citations from Greek authors illustrating usage. The 1940 edition is available online through Perseus.
Open-access: Logeion is an open-access database of Latin and Ancient Greek dictionaries. Developed in 2011, it is hosted by the University of Chicago. Apart from simultaneous search capabilities across different dictionaries and reference works, Logeion offers access to frequency and collocation data from the Perseus Project. Enter Greek words using Latin letters with the beta code.
Print, 3rd ed. (Chicago, 2000): Indispensable for the study of Early Christian literature, this new updated American edition of Walter Bauer's Wörterbuch zu den Schriften des Neuen Testaments builds on its predecessor's staggering deposit of extraordinary erudition relating to Greek literature from all periods. Including entries for many more words, the new edition also lists more than 25,000 additional references to classical, intertestamental, Early Christian, and modern literature.
(Coming soon!) Cambridge University Press will be publishing a new, two-volume Ancient Greek-English Lexicon. Instead of relying solely on existing lexicons, the editors have systematically gone back to the original texts in order to identify fresh interpretations and insights. Employing up-to date lexicographical practices, we provide not only single-word translations, but also detailed information on meaning, context and style. The Lexicon has been over 20 years in preparation.
Login required; by Marinos Yeroulanos (Tauris, 2016): This unique reference book offers one of the most comprehensive selections of Greek quotations ever committed to print. With its English text matched by the original Greek, the volume collects entries, ranging from the archaic period to late antiquity, and across philosophy, drama, poetry, history, science and medicine, each indexed with key words to enable fast sourcing. Together, these selections provide an incomparable insight into the glories of Greek civilization.
Print; by Richard J. Durling (Brill, 1993): This is a dictionary of Ancient Greek medical terms as culled from Galen's voluminous works, covering all medical fields: diet, drugs and surgery. It contains approximately 3,000 Greek words and 119,000 citations. Particularly rich is the vocabulary of plant names, which sometimes defy identification.
Open-access; by G. W. H. Lampe (Clarendon, 1961): This dictionary is one of the most comprehensive works ever compiled on the theological and ecclesiastical vocabulary of the Greek Christian authors, including material from Clement of Rome to Theodore of Studium. While intended to be used in conjunction with Liddell & Scott, it contains a very large number of words used by Christian authors not included in that lexicon.
Open-access: Wiktionary is a multilingual, web-based project to create a free content dictionary of terms (including words, phrases, proverbs, etc.) in all natural languages, including Ancient Greek. These entries may contain definitions, pronunciation guides, inflections, usage examples, and related terms, among other features.