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Penta- is a combining form used like a prefix meaning “five.” It is used in a great many scientific and other technical terms.

In chemistry, penta- is specifically used to indicate five atoms or five groups of atoms in compounds, e.g., pentazocine.

Penta- comes from the Greek ��é�Գٱ�, meaning “five.”

In Christianity, the Pentecost is a festival celebrated on the seventh Sunday after Easter. In Judaism, it refers to Shavuoth, a festival that commemorates God’s giving of the Ten Commandments to Moses. Pentecost takes its name from another Greek word closely related to ��é�Գٱ�, ���Գ�ŧ��Dz���ḗ, “fifttieth,” and was so named because Jewish Pentecost is observed on the fiftieth day (Greek, ���Գ�ŧ��Dz���ḗ ��ŧ��é����) after the second day of Passover.

In English poetry and drama, iambic pentameter is a line of verse that consists of five metrical feet (pentameter) in which the first syllable is unstressed and is followed by a stressed syllable (iambic). Shakespeare, among many others, most often wrote his plays in iambic pentameter.

What are variants of penta-?

When combined with words or word elements that begin with a vowel, penta- becomes pent-, as in pentane.

One example of a word you may have encountered that features penta- ������pentagon, “a polygon having five angles and five sides.”

The first part of the word, penta- means “five.” The -gon portion of the word may also look familiar: it is a combining form meaning “angled” or “angular,” from the Greek ��ō��í��. Pentagon literally translates to “five-angled.”

Pentagon comes from the Greek ���Գ�á��ō�ԴDz�, which features the equivalent form of penta- in the language.

The capital-P Pentagon, a massive building in Arlington, Virginia, containing most U.S. Defense Department offices, is the shape of a pentagon.

What are some words that use the combining form penta-?

• pentachloronitrobenzene
• pentadactyl (using the equivalent form of penta- in Greek)
• pentaerythritol
• pentagram (using the equivalent form of penta- in Greek)
• pentahedron
• pentameter (using the equivalent form of penta- in Greek)
• pentastome
• pentavalent

What are some words that use the combining form pent-?

• pentacle
• pentane
• pentangle
• pentene
• pentobarbital
• pentose
• pentoxide
• pentyl

What are some other forms that penta- or pent- may be commonly confused with?

• pan-
• panto-
• para-
• partheno-

Not every word that begins with the exact letters pent- is necessarily using the combining forming pent- to denote “five,” such as pent-up or penthouse. Unpack their history and meaning at our entries for the words.

The combining form -dactyl means “possessing fingers or toes.” A pentadactyl animal has how many digits on each hand or foot?