"'Twas not by ideas,---by heaven! His life was put in jeopardy by words." (1.2.15)
Here, Tristram explains that Toby is obsessed with building fortifications because he can't figure out exactly what happened at Namur. As with any professional jargon (try talking to a computer programmer, much less an English professor), military vocabulary is incomprehensible. Words matter, maybe even more than ideas. One way of thinking about this is to consider that Mr. Shandy is so obsessed with ideas that he constantly gets everything wrong; and Toby is so obsessed with words that he can't get anything right, either. Both of them, hearing the same word, imagine two entirely different things. Maybe Tristram's novel is trying to figure out the relationship between words and the ideas (or things) that they represent.
A woman moreover of few words and withal an object of compassion. (1.7.1)
The woman of few words is the midwife whose story Tristram tells at the beginning of the novel. "Withal" is an old-fashioned adverb (and sometimes preposition) that means something between "also" and "because." It's not exactly causal, but it's also not not causal. So being of few words seems to help make her an object of compassion, just like it's hard to feel sorry for people who constantly post veiled self-pitying updates on Facebook.
The many perplexities he was in arose out of the almost insurmountable difficulties he found in telling his story intelligibly, and giving such clear ideas of the differences and distinctions between the scarp and counterscarp,—the glacis and covered way,—the half-moon and ravelin,—as to make his company fully comprehend where and what he was about. Writers themselves are too apt to confound these terms (2.1.3-4)
Here, military language prevents Toby from understanding what happened to him at Namur. Confusing battle terms make telling a story impossible, so words and language seem to prevent meaning rather than help it along. Gee, it sounds like someone's been reading Tristram Shandy.
'Tis language unurbane,—and only befitting the man who cannot give clear and satisfactory accounts of things, or dive deep enough into the first causes of human ignorance and confusion. (2.2.5)
Who called the language police? Tristram says bad language is the recourse of people who can't express themselves any other way. Again, language provides an important clue to what's going on in someone's head: bad language, bad man; nice language, nice man. But … really? Tristram can't possibly believe this, can he?
O countrymen!—be nice,—be cautious of your language;—and never, O! never let it be forgotten upon what small particles your eloquence and your fame depend.
Particles are functional parts of language that don't change form, including prepositions and adverbs, as well as the interjections that help move words along—like "well," "alas," "hello." Tristram insists that every part of language matters, which is sort of obvious if you think about the difference between, "First, I took the bread out of the bag; second, I spread the peanut butter," and "First, I spread the peanut butter; second, I took the bread out of the bag."
You must know, my uncle Toby mistook the bridge—as widely as my father mistook the mortars. (3.23.2)
Here, "bridge" and "mortar" mean two different things at the same time. To Toby, they have military meaning; to Walter, they have philosophical meaning. Some words—the good words, maybe—don't have fixed meanings and can only be understood in context. Because people provide context, language becomes individual.
But the word siege, like a talismanic power, in my father's metaphor, wafting back my uncle Toby's fancy, quick as a note could follow the touch—he open'd his ears. (3.41.2)
Like spells, words have power to make things happen. We know this: in a marriage ceremony, you have to agree ("I do") before it's valid. They're so powerful that Toby is helpless to change his behavior: as soon as he hears the word 'siege,' he starts thinking about fortifications.
The best word, in the best language of the best world, must have suffered under such combinations. (6.1.34)
Again, words don't have fixed meanings. They can change when people start using them differently or when they gain new associations. Tristram refers to this (probably ironically) as "suffering," but language can gain a lot when it changes. If it couldn't change, we'd never be able to "friend," to "tweet," or, thanks to Shakespeare, to "puke."
There are two certain words, which I have been told will force any horse, or ass, or mule, to go up a hill whether he will or no; be he never so obstinate or ill-will'd, the moment he hears them utter'd, he obeys. They are words magic! cried the abbess in the utmost horror—No; replied Margarita calmly—but they are words sinful. (7.24.2)
Here's another example of words being both powerful and dangerous, and maybe dangerous because they are powerful. Swearing at horses makes them move, but it might make you move—in the wrong direction—at the same time. Like rubbing your head and your tummy?
This is not a distinction without a difference. It is not like the affair of an old hat cocked—and a cocked old hat, about which your reverences have so often been at odds with one another—but there is a difference here in the nature of things—(8.10.3-4)
Language doesn't come after meaning but actually changes meaning when it's said. The example Tristram gives here is the word "cocked" coming before and after the phrase "old hat." He insists that the two positions change not just the meaning of the phrase but also the very thing that the phrase represents.