ichidan verb / intransitive verb:

• to stretch; to extend; to lengthen; to grow (of hair, height, grass, etc.)
• to straighten out; to be flattened; to become smooth
• to spread (of paint, cream, etc.)
• to stretch out (e.g. of a hand); to extend
• to lose elasticity; to become slack; to become soggy (e.g. noodles)
• to make progress; to develop; to expand; to increase; to improve ［伸びる］
• to be exhausted; to be groggy; to pass out; to collapse ［伸びる］
• to be prolonged (meeting, life span, etc.); to be extended (e.g. deadline); to lengthen (e.g. of the days) ［延びる］
• to be postponed; to be delayed; to be put off ［延びる］