Undefined classification terms require ordinary meaning; PTFE products were not proved rigid, so duty and penalty failed.

PTFE sheets, boards, films and allied products were not shown to be rigid articles for central excise classification because the term "rigid" was undefined during the relevant period and had to be given its ordinary or dictionary meaning. The record did not contain conclusive technical or ordinary evidence establishing that the goods met that description, and the departmental material was insufficient to place them in the duty-bearing category. As a result, duty could not be sustained on that classification basis and the penalty also failed.

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Issues: Whether the PTFE sheets, boards, films and allied products manufactured by the appellant were rigid articles so as to attract central excise duty and the penalty imposed under the Central Excise Rules, 1944.

Analysis: The applicable exemption and tariff treatment turned on whether the goods could properly be characterised as rigid plastic boards, sheetings, sheets or films. In the absence of any statutory definition of "rigid" during the material period, the expression had to be understood in its ordinary or dictionary sense. The record did not contain conclusive evidence, either by acceptable technical standard or by ordinary meaning, to show that the goods removed by the appellant were rigid. The materials relied upon by the department were found insufficient to sustain the conclusion that the goods fell within the duty-bearing category.

Conclusion: The goods were not proved to be rigid articles liable to duty, and the penalty could not be sustained. The appeal succeeded.

Ratio Decidendi: Where a charging or exemption provision uses an undefined expression, classification must be determined according to its ordinary or dictionary meaning, and duty cannot be upheld without conclusive evidence that the goods answer that description.

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