A stiffener, in engineering and design, is a structural element added to a structure to increase its rigidity and strength. Stiffeners are commonly used in various applications, such as in the design of beams, plates, and other structural components

Apex haunch" isn't a standard engineering term that I'm familiar with, and it might be a specialized or contextspecific term used in a particular field or industry. Without additional context or specific details, it's challenging to provide a precise definition.

Base plate is a flat, typically rectangular, metal plate used as a foundation or support for a structure or machine. It serves to distribute the load from the supported object to the underlying foundation or surface. Base plates are commonly used in construction, engineering, and machinery applications.