In the Linux world, the term IP masquerading often is used for historical reasons. In pre-iptables times, the masquerading engine was separate from the packet filter and stateful inspection engine. In a way, IP masquerading is a point of view that emphasizes the stealthy character of the procedure. In contrast, PAT describes the mechanism more accurately.
NAT gateways (NAT translators in Internet Engineering Task Force [IETF] parlance) internally operate as TCP/UDP port multiplexing/demultiplexing engines. This procedure also is referred to as mapping and reverse mapping. NAPT is IETF parlance for PAT.
You occasionally will find that Cisco differentiates between NAT and PAT. From the Cisco perspective, this is a differentiation of one-to-one and many-to-one/many-to-many mappings.