The longest word in the world is Greek; 175 letters and 78 syllables

We Greeks are known for very long names, smashing world records, and inventing all manner of stuff first, but not even that could prepare anyone for the world's longest word which is the creation of one of our ancestors:  Aristophanes.

According to the Guinness Book of World Records, the name of a fictional dish created by Aristophanes in his comedy Assembly women (Eκκλησιαζουσες). 

It consists of with 175 letters and 78 syllables whilst the transliteration has 183 Latin characters.

The word:

Lopado­temacho­selacho­galeo­kranio­leipsano­drim­hypo­trimmato­silphio­karabo­melito­katakechy­meno­kichl­epi­kossypho­phatto­perister­alektryon­opte­kephallio­kigklo­peleio­lagoio­siraio­baphe­tragano­pterygon

Or in Greek:
λοπαδο­τεμαχο­σελαχο­γαλεο­κρανιο­λειψανο­δριμ­υπο­τριμματο­σιλφιο­καραβο­μελιτο­κατακεχυ­μενο­κιχλ­επι­κοσσυφο­φαττο­περιστερ­αλεκτρυον­οπτο­κεφαλλιο­κιγκλο­πελειο­λαγῳο­σιραιο­βαφη­τραγανο­πτερύγων.

According to Wikipedia in one dictionary, it is defined as a "name of a dish compounded of all kinds of dainties, fish, flesh, fowl, and sauces".

The dish was a fricassée, with at least 16 sweet and sour ingredients, including the following:

Fish slices
Fish of the elasmobranchii subclass (a shark or ray)
Rotted dogfish or small shark's head
A generally sharp-tasting dish of several ingredients grated and pounded together
Silphion, possibly a kind of giant fennel, now believed extinct
A kind of crab, shrimp, or crayfish
Honey poured down
Wrasse (or thrush)
A kind of sea fish or blackbird as topping
Wood pigeon
Domestic pigeon
Rooster
The roasted head of dabchick
Hare, which could be a kind of bird or a kind of sea hare
New wine boiled down
Wing and/or fin