white thread
Refers to thread that is white in color, often used in weaving, sewing, or as a metaphor for something pure or delicate.
着物の縫い目に白糸が使われている。
White thread is used in the seams of the kimono.
Compound of 白 (しら, white) and 糸 (いと, thread). The reading しらいと is a straightforward combination of the kun'yomi readings.