continuing for a long time
enduring, unending
Cases of word usage
1) lasting for two years (biennial)
2) without beginning or end; lasting for ever (eternal)
3) (of something lasting for a period of time) to come to an end (expire)
4) the ending (of something lasting for a period of time) (expiry)
5) lasting for a short time (fleeting)
6) lasting for, done in, a very brief period of time (momentary)
7) of a monument; (of books, studies etc) of lasting value; very great (monumental)
8) continuing throughout the whole year; lasting for a very long time; living for more than two years (perennial)
9) lasting for, designed to be used for, a limited time only (temporary)
10) lasting for a short time only (transient)