Final answer:
Delegation is the transfer of higher-level leadership responsibilities to lower-level leaders, a trend becoming more common as organizations shift towards flat structures to increase responsiveness.
Step-by-step explanation:
The term that is best described as traditionally higher-level leadership responsibilities being transferred to leaders at lower levels is delegation. Delegation is a management strategy where authority and responsibilities are transferred to lower-level leaders. This contrasts with a hierarchical system where decisions flow from the top down. Within the context of organizational behavior, the trend toward flat organizational structures has led to more delegation, empowering lower-level employees to make decisions that were once reserved for those at higher levels in the hierarchy of authority. This shift helps organizations to become more agile and responsive in a rapidly changing business environment.