æz ɐ kˈɑːnsɛpt, ɐ lˈaɪf kˈoːɹs ɪz dᵻfˈaɪnd æz "ɐ sˈiːkwəns ʌv sˈoʊʃəli dᵻfˈaɪnd ᵻvˈɛnts ænd ɹˈoʊlz ðætðɪ ˌɪndᵻvˈɪdʒuːəl ɛnˈækts ˌoʊvɚ tˈaɪm" dʒˈiːl ænd ˈɛldɚ nˈaɪntiːnhˈʌndɹɪd nˈaɪnti ˈeɪt, pˈiː. twˈɛnti tˈuː.
As a concept, a life course is defined as "a sequence of socially defined events and roles that the individual enacts over time" (Giele and Elder 1998, p. 22).