linen tester

English

a linen tester, a small magnifier

Etymology

From linen +‎ tester.

Noun

linen tester (plural linen testers)

1. A folding magnifying glass which, when unfolded, forms a frame for the lens at a pre-focussed distance. Commonly used in stamp collecting.
2. A small magnifying glass, as might be used to check the thread count of linens.

References

• “linen tester”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.