A group of herbalists, including one in Maine, is being sued by a Massachusetts company for trademark infringement over use of the name “Fire Cider” to sell their own versions of a spicy herbal tonic produced by the plaintiff.

However, the defendants say fire cider is a generic term used by thousands of herbalists that predates the trademark’s registration date by 40 years.

In a lawsuit filed in U.S. District Court for the District of Massachusetts in mid-April, Pittsfield-based Shire City Herbals Inc. accuses Katheryn Langelier of Union, Maine, Nicole Telkes of Austin, Texas, and Mary Blue of Providence, Rhode Island, of infringing on the Fire Cider trademark, which Shire City registered with the U.S. Patent and Trademark Office in December 2012. Langelier’s business is Herbal Revolution Farm and Apothecary.

The product is a mixture of “certified organic apple cider vinegar, organic oranges, lemons, honey, turmeric, garlic, ginger and habanero peppers,” according to the legal complaint. Shire City also is the registered user of the domain name firecider.com.

The civil lawsuit seeks $100,000 in damages for trademark infringement, and for interfering with Shire City’s ability to do business when the group challenged the trademark’s validity in a pending cancellation proceeding before the trademark office’s Trademark Trial and Appeal Board.

“Defendants’ conduct has caused confusion among consumers as to the source of origin of (the) defendants’ products,” the Shire City lawsuit states.

The three defendants, all of whom are small-business owners, responded Tuesday in a news release by saying that Shire City has no right to own the trademark because fire cider is a generic term that has been used by herbalists for decades.

“Words that are the name of a product itself (like “Fire Cider” or “Bloody Mary”) are not trademarks, so others are free to use them to describe or identify their goods,” the herbalists’ attorney, Rita Heimes of Verrill Dana in Portland, said in the release.

Blue, the Providence-based defendant and owner of Farmacy Herbs, has started an online petition to revoke the “fire cider” trademark on Change.org, an online petition website. As of Tuesday, the petition had garnered 9,572 signatures.

The petition Web page states that the term actually was coined in the 1970s by noted herbalist Rosemary Gladstar, who intended for it to be used freely by everyone. “Trademarking this name is like trademarking the word ‘pizza,’ ” it says.

The defendants have until Monday to file a legal response to Shire City’s complaint.