[tim-ber-lahyn] 
| 1. | the altitude above sea level at which timber ceases to grow. |
| 2. | the arctic or antarctic limit of tree growth. |
| timberline (tĭm'bər-līn') Pronunciation Key
A geographic boundary beyond which trees cannot grow. On the Earth as a whole, the timberline is the northernmost or southernmost latitude at which trees can survive; in a mountainous region, it is the highest elevation at which trees can survive. Also called tree line. |
bərˌlaɪn