perennial

Concise Oxford English Dictionary © 2008 Oxford University Press:
perennial/pəˈreniəl/

▶adjective

• 1 lasting for a long time; enduring or continually recurring.

  ■ continually engaged in a specified activity: a perennial student.

• 2 (of a plant) living for several years. Compare with annual, biennial.

• 3 (of a stream or spring) flowing throughout the year.

▶noun a perennial plant.

– derivatives
perennially adverb.

– origin C17 (in the sense ‘remaining leafy throughout the year, evergreen’): from L. perennis ‘lasting the year through’ + -ial.