Look up the word "revolutionary." Regardless of which dictionary you consult, you're probably going to find a definition along the lines of "causing a major change."

As is the case with other bold adjectives, revolutionary is sometimes used to describe things that really don't live up to the billing. That's especially true when stocks are involved. However, there are some stocks that truly deserve the label. Here are three revolutionary stocks I'd buy right now without hesitation (listed in alphabetical order).

1. Intuitive Surgical

Sure, Intuitive Surgical (ISRG 0.59%) has been selling its da Vinci robotic surgical systems for over 20 years. It's still a revolutionary company and stock, though, in my view. After all, we're talking about robots helping surgeons perform medical procedures on humans.

I'll readily admit that I would hesitate quite a bit with most stocks that trade at a forward price-to-earnings multiple of 43x. Actually, I'd pass most of them up altogether. However, it's a different story with Intuitive Surgical for a couple of key reasons.

First, the company has a huge head start over its rivals. Nearly 8,300 da Vinci systems are installed worldwide plus a growing number of Ion robotic systems used in bronchoscopy. Existing customers are unlikely to throw away their investment in training to go with a competitor. New customers will have to think long and hard about selecting a robotic system that can't compare with Intuitive's extensive track record.

Second, the growth opportunities for Intuitive Surgical are simply too big to ignore. This year, da Vinci systems will be used in around 2.1 million procedures. Intuitive estimates that there are roughly 6 million procedures performed annually for which it already has products and regulatory clearances in place. And there are another 14 million or so procedures performed each year that the company can target with new products and clearances in development.

2. TransMedics Group

Organ transplantation is a market in dire need of a revolution. Way too many donor organs don't survive long enough to be used in patients. The numbers are especially horrific for lungs, with a whopping 83% of donor organs going unutilized. TransMedics Group (TMDX 3.17%) is bringing the needed change to this market with its Organ Care System (OCS).

Most donor organs today are transported using cold storage. OCS keeps hearts, livers, and lungs alive during transit. As a result, utilization rates for donor organs with OCS soar to more than 80%. Severe post-transplant complications are also drastically reduced.

One key roadblock for TransMedics' growth has been the lack of availability of airplanes to transport donor organs. The company is addressing this issue head-on with its recent acquisition of charter flight operator Summit Aviation. With Summit, TransMedics will have its own aviation network -- the only one in the country dedicated exclusively to transporting organs.

TransMedics' market cap currently stands below $2 billion. As the company disrupts the organ transplant market over the next few years, I predict it will grow significantly larger.

3. Vertex Pharmaceuticals

Vertex Pharmaceuticals (VRTX -0.06%) continues to deliver revolutionary therapies to cystic fibrosis (CF) patients. Its four approved drugs are the only ones that treat the underlying cause of CF. But Vertex has more game-changers likely on the way.

We can start with curing rare blood disorders sickle cell disease and transfusion-dependent beta-thalassemia. Vertex and its partner CRISPR Therapeutics await U.S. and European regulatory approvals for gene-editing therapy exa-cel in both diseases.

You've probably heard about the serious issues involved with opioid drugs. Vertex could soon bring a powerful non-opioid therapy to market for alleviating acute pain with VX-548. The big biotech expects to report results from three late-stage studies of VX-548 in early 2024.

Vertex is also evaluating inaxaplin in a pivotal clinical study targeting APOL1-mediated kidney disease (AMKD). There currently are no approved therapies for treating the underlying cause of AMKD, which affects more patients globally than CF.

Last but not least, Vertex is the clear leader in developing a potential cure for type 1 diabetes (T1D). The company's pipeline includes three T1D programs in clinical testing.

A revolutionary stock? One that I'd buy without hesitation? The answers are resoundingly "yes" to both with Vertex.