Synonyms or not?

In German, if you change the prefix to a word, especially a verb, you get a completely different word. Brauchen means “need,” but gebrauchen means “buy.” English is less rigorous. Lots of times we add a prefix or suffix to a word and get the same meaning. I think we want to say the word more strongly, so we add a random syllable someplace. Today I’ll remind you of a few of them, and make the better choice bold. Perhaps you can add to the list.

Flammable and inflammable. I have a comic for this one:

I wonder who those two guys are.

The comments on this comic are funny, too.

Preventive and preventative. The latter is generally considered low class.

Valuable and invaluable. I suppose the latter literally means “having a value that can’t be calculated,” but we have the perfectly good word “priceless” for that.

Regardless and irregardless. Never use “irregardless”! It’ll peg you as semi-literate in an instant, and you’ll become an object of derision by curmudgeons everwhere.

Caregiver and caretaker. These two are synonyms when they refer to someone who deals with the elderly. I think “caregiver” is a result of marketing efforts in the elder-care industry, and I think the word does have nicer connotations than caretaker, which can also apply to animals and gardens. You’re a caretaker, not a caregiver, at the zoo.

Burn up and burn down. Okay, there’s a distinction here if you care to make it. “Burn up” means completely consumed by fire, and “burn down” refers to a structure such as a house. “Burned up” is more general.

Titled and entitled. Here’s an example of two words that have separate meanings in different contexts. Titled can mean you’re a Duke or something like that, and entitled can mean you have permission to possess something. But when you refer to the name of a book, you should say the book is titled Thus and So.

Okay—your turn what are your favorite meaningless prefixes and suffixes?