A.k.a.

"Also Known As"

Sometimes people are known by more than one name:

intentionally tried to hide real identity

change in marital status

A.k.a. is pronounced as three individual letters

EX:  Jane Single becomes married and changes her name to Jane Married.  Some legal documents might show her name as "Jane Married, a.k.a. Jane Single"

D.b.a.

"Doing Business As"

Certain business entities are just an extension of the owner; aren't truly recognized as a separate entity at law.

Small business owned by one person and not incorporated.   While not legally separate from the owner, it operates under a different name.  D.b.a. is pronounced as three individual letters, and not as a word.

EX:  Paul owns and works in a small grocery store called Marin Market.  Sally slips and falls while in the market.  She would sue Paul as:  "Paul, d.b.a. Marin Market"

Et al.

"And Another"

Frequently two people are opening a business venture together, and for brevity and convenience only, the first person is listed, and a notation is made showing there are other people involved.  

Et al. stands for et alius, which is why there is a period after the "l" in "al"

Common usage:  Technically et al. refers to just one other person, but it is common practice in CA, for it to signify any number of additional people.

EX:  John and his sister Robin own a home together.  In some legal documents after John and Robin have been previously identified, they might be referred to as "John et al."

Et Ux.

"And Wife"

Because of the sexist connotation of naming only the husband by name, this abbreviation is seldom used, except perhaps on old deeds and state exams.  Et. ux. stands for "et uxor" which is why there is a period after the "x" in "ux"

EX:  The property is owned by "John et ux."

Opposite word:  "and husband" - "et vir".  Extremely rare.

Etc.

"And Similar Type Things"

Means "other things of a similar type, character, or nature."  Period after "c" - abbreviation is short for et cetera.

EX:  The house contained the usual assortment of chairs, tables, lamps, etc.

Ex Rel.

"Upon the Relation or Report"

Ex Rel. is the abbreviation for "ex relatione" 

Sometimes private citizens have an interest in the outcome of a case.  In most of these types of cases, it is a private citizen who does the initial investigation and brings the matter to the attention of the government.

When litigation is instigated by information supplied by a particular person, or the government sues on behalf of a particular person, that person is named in the caption.  The person has an interest in the outcome of the case and is often the real-party-in-interest.

EX:  Dick discovers Peter has been trading in his company's stock based on inside information illegally obtained.  Dick induces the SEC to prosecute and to recover the illegally obtained profits for Dick's company.  The caption of the complaint would read:  "United States ex rel. Dick vs Peter"