octa-

1. a combining form occurring in loanwords from Greek and Latin, where it meant “eight” ( octagon; octastyle ), on this model, used in the formation of compound words, and in chemical terms specialized to mean “having eight atoms” ( octavalent ).

octa

¹

/ ˈɒktə /

noun

1. a variant spelling of okta

octa-

²

combining_form

1. a variant of octo-

Word History and Origins

Origin of octa-¹

< Greek okta-, combining form of oktṓ eight

Example Sentences

“OCTA and Metrolink emergency crews worked on full steam to build the catchment wall, resulting in construction progressing ahead of schedule,” Orange County Supervisor Katrina Foley said in a statement.

From Los Angeles Times

The emergency declaration allows the OCTA, which owns that section of the rail line, to access up to $10 million in immediate emergency repair funding.

From Los Angeles Times

OCTA’s board of directors declared an emergency in June to fast-track construction of the wall.

From Los Angeles Times

“We told them we needed time to review it, and come back on Friday to talk to us,” said Joel Zlotnik, spokesperson for the OCTA.

From Los Angeles Times

The union also represents OCTA’s bus operators, who reached a three-year contract with the agency in February.

From Los Angeles Times

Words That Use Octa-

What does octa- mean?

Octa- is a combining form used like a prefix meaning “eight.” It is often used in a great many scientific and technical terms.

Octa- comes from Greek oktṓ, meaning “eight.” The Latin equivalent, which is almost identical in spelling and pronunciation, is octō.

What are variants of octa-?

When combined with words or word elements that begin with a vowel, octa- becomes oct-, as in octane. Another variant of octa- is octo-, as in octofoil.

Want to know more? Check out our Words That Use entries for both oct– and octo-.

Examples of octa-

An example of a word you may have encountered that features octa- is octagon, “a polygon having eight angles and eight sides.” Octagon comes from Greek oktágōnos, which features the equivalent of the form octa-.

We know octa- means “eight,” but what about the -gon portion of the word? The form -gon, from Greek gōnía, means “angled, angular.” Octagon literally translates to “eight-angled.”

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

• octachord (using the equivalent form of octa- in Greek)
• octahedron (using the equivalent form of octa- in Greek)
• octameter (using the equivalent form of octa- in Greek)
• octastyle
• octavalent

What are some other forms that octa- may be commonly confused with?

• oc-
• oculo-
• ocy-
• oleo-
• ont-
• onto-
• opto-
• oto-
• oxo-

Break it down!

The combining form -hedron means “face” and is used in the names of geometric figures with a certain number of faces. With this in mind, what is an octahedron?