Inexpressive (adjective)

Not capable of or not showing emotion or feeling.

Origin:

Derived from the latin word 'inexpressus' meaning not expressed or hidden.

Examples:

1. Her inexpressive demeanor made it difficult for others to know what she was feeling.
2. The inexpressive sculpture left visitors unimpressed and unemotional.
3. The inexpressive performance left the audience feeling unsatisfied and bored.
4. His inexpressive face gave away nothing about his thoughts or feelings.
5. Her inexpressive voice made it hard for the teacher to gauge her understanding.