Illustrated Biology Dictionary

The Biology Dictionary features thousands of detailed, often encyclopedic definitions, the vast majority illustrated with photographs (93%). The alphabetical glossary provides fast navigation by listing all terms and expressions starting with each of the 26 letters of the English alphabet.

Biology, Botany, Zoology, Ecology & Aquarium Dictionary

The Dictionary of Life is dedicated to biology, encompassing zoology, botany, and ecosystems. Composed of thousands of illustrated scientific definitions, it answers key questions across the life and earth sciences: the cell, health, microbiology, aquaculture and ichthyology, aquaponics and permaculture, gardening, medicinal plants, and more.

Historically, the Biological Dictionary was created in 2007 to answer questions about H2O, fish, and aquatic plants, and has expanded over the years to cover all branches of the life sciences.

To go even deeper into scientific terminology, understanding the history and origin of words is essential: What is etymology?

Useful Dictionary Searches

The internal search engine of our English biological dictionary, located at the top of every page, lets you explore groups of words (nouns, adjectives, verbs, adverbs) or compound phrases—especially useful for searching common Greek and Latin roots, prefixes, or suffixes. Here are a few helpful starting queries:

• terms containing fish;
• terms containing plant;
• terms containing aquarium;
• terms containing aquatic;
• terms containing water;

This list also includes direct access to scientific suffixes used to describe specific feeding habits and trophic modes:

• the suffix -phage or -phagy;
• the suffix -vore or -vorous;
• the suffix -troph or -trophic;

Feel free to use our contact form to suggest any search topic or term you would like to see added. Every request or suggestion is reviewed by our editorial team.

Grammatical, Plural & Taxonomic Conventions

Unlike English—where nouns and adjectives have no grammatical gender and verbs follow simplified inflections—scientific taxonomy and biological terminology rely heavily on classical Latin and Greek rules. Each dictionary entry indicates its English part of speech (noun, adjective, transitive or intransitive verb, plural noun, abbreviation, or adverb) alongside any irregular classical plural forms (such as larva / larvae, bacterium / bacteria, fungus / fungi, taxon / taxa, or genus / genera).

Here are also the basic rules for spelling and understanding a Latinized binomial species name. A scientific binomial consists of a genus name (a singular noun that is masculine, feminine, or neuter in Latin) followed by a specific epithet (usually an adjective) that must agree in grammatical gender with the genus—even though English itself makes no gender distinction.

Taxonomic Latin in biology, botany, and zoology is far simpler than classical Latin, yet knowing the gender of the genus explains why species endings change when a species is reclassified into a different genus:

• Masculine genera typically end in:
  • -us (except tree names);
  • Greek endings in -on (except -dendron).
• Feminine genera typically end in:
  • -a (except Greek endings in -ma);
  • classical tree names ending in -us;
  • endings in -ago, -ix, -odes, -oides, -is, and -es.
• Neuter genera typically end in:
  • -um;
  • Greek endings in -ma;
  • endings in -dendron.

Because the specific epithet acts as an adjective modifying the genus, its ending changes according to the genus's gender:

• adjectives in -us take -a in the feminine and -um in the neuter (e.g., robustus, robusta, robustum);
• adjectives in -er take -ra / -rum (e.g., niger, nigra, nigrum) or -ris / -re (e.g., acer, acris, acre);
• adjectives in -is remain -is in the feminine and take -e in the neuter (e.g., utilis, utilis, utile);
• all other endings remain invariable, including present participles in -ens (e.g., repens) or -ans (e.g., candicans).

A few specific epithets are not nominative adjectives: they are either proper nouns in the genitive case honoring a person (e.g., debelius in Lysmata debelius, or terveri), genitive plural nouns indicating geographic or ecological origin, or nouns in apposition (former genus names) that remain invariable regardless of the genus gender.

Synonyms, Antonyms & Multilingual Translations

The Dictionary of Life also provides extensive synonyms and antonyms—not only for single nouns or adjectives, but also for multi-word scientific phrases. Most biological terms and expressions are cross-linked with their French and Spanish translations, making it easy to switch between languages. Built to go well beyond a standard general dictionary, this glossary serves as a dedicated English reference work for biology, botany, zoology, and aquariology.