I have already mentioned stolid and solid; how about
kudu: antelope
kudzu: vine
And indeed “grizzly” as in bear. Or “grizzled/grizzly” as in a whimpering toddler.
Kudu is also a type of gourd/squash with large leaves. It’s often grown over a pergola to provide shade as well as food, and immigrants from South Asia keep up the custom in my part of London. A photo I posted on another site of a market stall advertising kudu plants caused some conniptions among US-based members!
I’ve seen a spellchecker confuse “Catholic” and “Cthulhu”.
Which led immediately to “does the spellchecker know something we don’t?” jokes.
monorchism: one testicle
monarchism: rule by a single head of state
Monomonarchism: rule by a single head of state with one testicle.
Perhaps “monorchmonarchism”? 
Monoecious; plants with flowers of both sexes on a single plant.
Contrasted with;
Dioecious; plants with flowers of only one sex on each plant, requiring cross-pollination with a different plant.
I always get those two confused. Is it mono- because they are both on one plant, or di- because there are two different plants neccesary? Aggh.
Could be worse. A “haploid” cell has one set of chromosomes, because that’s half the usual number. A “diploid” (or “triploid”, or “quadruploid”…) cell has two (or three or four…) sets of chromosomes.
But you’d think that there’d be something between “half” and “two”. What would a monoploid cell be?
I just learned these words from you. Maybe it’s a sign of my perverted mind, but I immediately thought. “Mono’s can productively play with themselves. It takes just 1 to tango.” Maybe that’ll be mnemonic enough for you. 
Anything where 2 is the usual quantity raises that issue.
Funny but I was dealing with that exact issue at Amazon yesterday. I was buying a product that comes from the factory in a package of 2 identical items. Which Amazon then bundles into offering 1 or 2 or 3 of those 2-packs. But their terminology was inconsistent between the descriptive text and the ordering options. When you order quantity “2”, are you ordering 2 items = one package, or 4 items = 2 packages of 2? By looking at the 3-pack option, which had to be 3 packs of 2 since the items can’t be had singly at all, I concluded that “1 (pack of 1)” had to really mean “1 bundle of one package of 2 items”. Gaah!
Further muddying the waters, the factory also offers the same item in different quantity packs, including singly, but those at least are a different Amazon SKU on a different Amazon page.
Mitosis creates two identical body cells for growth and repair
Meiosis produces four unique sex cells (gametes) for sexual reproduction.