'Trekker' definitions:

Definition of 'trekker'

(from WordNet)
noun
A traveler who makes a long arduous journey (as hiking through mountainous country)

Definition of 'Trekker'

From: GCIDE
  • Trekker \Trek"ker\, n. [D.] One that treks. [Written also trecker.] [South Africa] --James Bryce. [Webster 1913 Suppl.]