Ob-

#prefix #etymology Published: 2021-11-22

In my past posts, I wrote about several words that contain the prefix “ob-“, such as obstetrician, obloquy, occult, etc. However, I didn’t really know how exactly they are formed and what they can possibly mean, so let me examine this prefix a bit deeper in this post.

Formation

According to the OED, the formations with the prefix “ob-“ in Latin occur as follows:

In combination with verbs and their derivatives, the b of classical Latin ob is assimilated to certain consonants, becoming oc- before c- , of- before f- , op- before p- , and apparently o- before m- (in omittere ).

Simply put, “ob-“ just gets assimilated depending on the first letter of the following element. There don’t seem to be many exceptions.

Meaning

The Latin preposition “ob” has a lot of meanings, all of which can be found in some English words. It has the following meanings:

1. in the direction of, towards
2. against, in opposition
3. over, down
4. completely
5. inversely

The sense 1, 2, and 3 are pretty similar to each other, and most basic words with this prefix can be considered to have the meaning 1 or 2: object, obey, obstacle, obtrusive, obligation, opponent, obloquy, and so on. Words that can be interpreted as sense 3 include oppress, obduct (to cause a plate to move sideways over the adjacent plate).

The words with the meaning 4 include obtain (with the Latin “teneō”, meaning “I hold”), occupy (with the Latin “capiō”, meaning “I take”), etc.

The last meaning is a bit different from the others, and the only word with this meaning that I personally came up with is, oblong, that usually means “a rectangle with the adjacent sides unequal”.