Rose Mattus, who with her husband, Reuben, turned a family-owned ice cream business in the Bronx into a national brand with the invented name Häagen-Dazs, died Tuesday in Westwood, N.J. She was 90 and lived in Cresskill, N.J.

The death was confirmed by Brian McNamara of Gutterman & Musicant Funeral Directors in Hackensack, N.J.

Around 1960, while sitting on their couch in the Bronx, Mr. and Mrs. Mattus fabricated the foreign-sounding name. It was Mr. Mattus’s idea to include a map of Denmark on the carton and to put an umlaut over the first “a” in Häagen, even though no umlaut is used in Danish.

In the company’s early years, Mrs. Mattus, the company’s controller, built the business by going to bodegas and grocery stores to offer free samples. By 1983, when Häagen-Dazs was acquired by Pillsbury for $70 million, the company had a strong presence in supermarkets, a coast-to-coast string of franchise ice cream shops and sales of about $115 million a year. It is now owned by Nestlé.