penta-

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 pénte, 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 pénte, pentēkostḗ, “fifttieth,” and was so named because Jewish Pentecost is observed on the fiftieth day (Greek, pentēkostḗ hēmérā) 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- is 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 gōnía. Pentagon literally translates to “five-angled.”

Pentagon comes from the Greek pentágōnon, 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?