Final answer:
The cell adaptation when columnar ciliated epithelial cells are replaced by stratified squamous epithelial cells in the bronchial lining is called metaplasia.
Step-by-step explanation:
When normal columnar ciliated epithelial cells of the bronchial lining are replaced by stratified squamous epithelial cells, the type of cell adaptation that occurs is metaplasia. Metaplasia is a process where one type of mature epithelial cell is replaced by another cell type, often as a response to chronic irritation or inflammation. This process may serve as a protective mechanism initially, but it can also predispose the tissue to malignancy if the underlying cause of the irritation is not resolved.