One of your objectives in vocabulary study should be to concentrate on quality, rather than simply on quantity, when it comes to the words you choose to learn. To obtain a professional-grade vocabulary, you’ll want to select words that are precise in meaning and that will clarify rather than obfuscate your points. If you’re not using a system like Ultimate Vocabulary that provides you with advanced levels for vocabulary study, a good place to start looking for words is at their origins, by looking up etymology. If you focus on one particular word origin or word root, you’ll be able to learn several related words that you can mentally group together, which will help you remember them in the future. We’ve turned our dictionary to words that start with OB and that have at their base the Latin prefix ob-. Although this prefix can add several seemingly contradictory meanings to a word, including towards, away from, against, near, and about, the general sense of a word using this prefix is “connected to [something].” Take a look at the words below – or should we say, observe the following:

obdurate (AHB-dur-et) adjective
Add the Latin word durus (“hard”) to the prefix ob- and you get a word that means “to be hard towards” – that is, to be adamantly opposed to something, stubborn.

obligation (ah-blih-GAY-shun) noun
Add the Latin verb ligare (“to bind”) and you get a word that means “to be bound to something” – that is, to be tied to it, required to do it.

obeisance (oh-BEY-suhns) noun
You’ll have to look backward twice for this word. First, add our prefix to the Latin verb audire (“to listen”) to get the verb to obey, then use the Old French version obeissant (“to be obeying”) of the verb; that leads you to the noun form of the word, obeisance, which means a bow or curtsey, signifying that you will be obeying the person you’re bowing to. If you need to obey someone, it’s because you have a tie or connection to them – an obligation, if you will.

oblivion (oh-BLIH-vee-uhn) noun
Add ob- to the Latin root livus (“smooth”) and you’ll get a word that can be used to mean “smoothed over” in the sense of “erased.” A state of oblivion means you’re not aware of what is around you, or what has happened in the past. Your memories have been wiped away.

obsolete (AHB-soh-LEET) adjective
In this case, the prefix ob- signifies movement away from the root word solere (“to be accustomed”), and gives you a word that means “out of customary use, outdated.”

Use these and other advanced English vocabulary words, and you’ll find there’s no obstacle to your success!