soap bubbles; soapsuds; lather
Refers to the foam or bubbles produced by soap, often when washing hands, face, or dishes.
When I washed my hands, a lot of soap bubbles came out.
I wash my face with soap lather.
Compound of 石鹸 (sekken, 'soap') + の (no, possessive particle) + 泡 (awa, 'bubble'). The exact historical derivation is straightforward; the spelling is conventionally associated with the meaning.