Question: SourceMeter or Source Measure Unit (SMU)?
Answer: A Source Measure Unit, shortened to SMU, is a particular class of instrument. Think of this phrase on the same level as oscilloscope or digital multimeter. They might also be known as source monitor units, source-measurement units, or other phrases that still shorten to SMU. In speaking the initialism should be pronounced as separate letters, "S-M-U", though you might hear it informally pronounced, "smoo".
SourceMeter® is the trademark name of Keithley source measure units. The SourceMeter name means your instrument has the quality, capability, and performance you can expect from Keithley source measure units. It is incorrect to use SourceMeter or sourcemeter to reference SMUs made by any other manufacturer.