The term 'of two parts' can be expressed as 'DUAL' in four letters. This term is used to describe something that is composed of two distinct parts, such as a DUAL-core processor or a DUAL-language education system. It can also refer to something that has two sides, such as a DUAL-sided coin or a DUAL-purpose tool. In general, the term 'DUAL' is used to describe something that is composed of two distinct parts or has two sides.