The Tertiary is a geologic period.

Tertiary (from Latin, meaning 'third' or 'of the third degree/order..') may also refer to:

• Tertiary (chemistry), a term describing bonding patterns in organic chemistry
• In biochemistry, the tertiary structure of a protein is its overall shape, also known as its fold
• Tertiary consumer, in ecology
• Tertiary feathers or tertials, feathers attached to humerus or inner portion of the wings of birds
• Tertiary color, a color made up by mixing one primary color with one secondary color, in a given color space
• Tertiary sector of the economy, or the service sector
• Tertiary education, educational levels following the completion of secondary education such as university or trade school
• Tertiary care, specialized consultative healthcare
• Tertiary, a member of a third order religious group
• Tertiary source, in research
• Tertiary stress, a proposed level of stress in phonetics

• Ternary (disambiguation)
• Secondary (disambiguation)
• Quaternary (disambiguation)
• All pages with titles beginning with Tertiary
• All pages with titles containing Tertiary