Every investor wants the kind of stock you can buy and forget about. These are the kinds of stocks that will rack up giant returns over time as their competitive advantages accrue, much as the FANG group of stocks has over the last decade. They often operate in timeless businesses that are insulated from broader changes in technology or consumer tastes.

If you're looking for stocks to deliver for your retirement or your kid's college fund, keep reading to see why our contributors recommend lululemon athletica (NASDAQ:LULU), Axon Enterprise (NASDAQ:AXON), and Under Armour (NYSE:UA) (NYSE:UAA) to buy and hold for the next 50 years.

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Hold that pose

Demitri Kalogeropoulos (lululemon athletica): My crystal ball gets cloudy looking out a couple of months, let alone five decades. But the results that Lululemon is putting up right now suggest it has a long runway of global growth ahead. The yoga-inspired apparel specialist recently trounced management's targets for the second straight quarter, as sales growth held steady at a 25% pace. Lululemon is firing on all cylinders right now, with customer traffic up in its stores and conversion rates improving in the booming online business, too.

Spiking profitability suggests that these gains could be the start of an impressive annual earnings spike for the retailer. They're evidence of skill at launching innovative products, after all, and they also confirm the premium status of this brand. Meanwhile, Lululemon's early success outside of its core yoga demographic means it could tap into big new categories over the next few years, like men's fitness, even as it extends its reach to markets like China.

Apparel can be a risky business, and lululemon knows that as well as any retailer could. But if it can keep its previous quality-control issues behind it while catering to its growing demographic, there's every reason to think its 2020 goal of $4 billion in annual sales is closer to the beginning of this growth story than the end.

You always need security

Jeremy Bowman (Axon Enterprise): Plenty of things will disappear over the next 50 years, but one thing that's guaranteed to remain is a need for security and law enforcement. Cue Axon Enterprise, maker of the Taser electroshock weapons and other high-tech policing tools like body cameras and in-car video systems. Axon has positioned itself effectively at a time of growing concern about police abuses, and the need for accountability seems likely to grow, especially as technology means tools like body cameras will only get better.

In addition to being the market leader in Taser-style conductive-electric weapons and body cameras, Axon also owns Evidence.com, the leading cloud-based digital evidence management software. The company's market leadership in those areas has created a strong foundation for growth as communities adopt better, safer, and more accountable policing tools.

Recent growth has been promising, with overall revenue up 25% to $99 million in the most recent quarter, and cloud-based revenue jumping 76% to $23 million. Growth in the cloud division has helped drive profits higher recently as earnings per share doubled to $0.18 in the most recent quarter. And the company is attracting new customers, including states like Tasmania in Australia, and the cities of Honolulu; Charlotte, North Carolina; and Calgary, Alberta.

As a result, Axon has been blowing past analyst expectations, and the stock has more than doubled this year. While that pace will probably slow, Axon is building a network of competitive advantages and barriers to entry that should pay off as needs for both security and accountability in law enforcement continue to grow.

Under Armour won't stay down forever

Steve Symington (Under Armour): Shares of Under Armour have fallen nearly 50% over the past two years, driven by a massive slowdown in its core North American business amid multiple sporting-goods retailer bankruptcies in 2016. That prompted the performance-apparel and footwear specialist to pursue a major business restructuring over the past year, to revitalize growth and better position itself for long-term success.

After bouncing back nicely from its multiyear lows late last year, however, Under Armour stock pulled back again after the company told investors it had identified $80 million in additional restructuring initiatives (bringing the total cost to a pre-tax range of $190 million to $210 million). Today, we're talking about a mid-cap business valued at $8.2 billion -- a tiny fraction of the $133 billion market cap commanded by Nike, its most prominent competitor.

But largely lost in its latest restructuring news was that Under Armour's North American business finally returned to growth, however modest, with quarterly sales up 1.6% to $843 million. And all the while, the relative outperformance of its international business -- where sales soared 28% to $302 million -- effectively highlights the incredible global runway for growth the Under Armour brand enjoys.

Make no mistake: Under Armour still has plenty of work to do before it revisits its all-time highs. But I think this is a lasting brand that will be around for decades to come. And I believe the recent pullback is a fantastic opportunity for patient investors to buy before the fruits of its restructuring are fully realized.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.