An unwieldy object is difficult to move or handle because it is heavy, large, or a strange shape.

A piano is a very unwieldy item to get down a flight of stairs. 钢琴是个很难搬下楼梯的物件。

An unwieldy system is slow and not effective, usually because it is too big, badly organized, or involves too many different organizations or people.

One disadvantage for the bank is that its huge size - over 15,000 staff - makes it unwieldy and slow-moving. 该银行的一大弊端是机构庞大——有15 000多名员工——造成效率低下及运营缓慢。