Sleek/Slick, Especially/Specially Interchangeable?

I am having a hard time differentiating between these terms. Are they interchangeable in most contexts?

The Cambridge dictionary lists "specially" as a variant of "especially." Moreover, Dictionary.com lists "sleek" as a variant of "slick." Given the credibility of these two sources, I'd say you're okay with saying they're interchangeable. However, their uses generally do differ in everyday speech.

"Especially" is generally used to mean "particularly" etc.:

"Students interested in languages should use the Antimoon forum, especially those who are learning English."

"Specially" is usually used when referring to goods, services, programs etc:

"These cars are specially made to be emit less pollution."

"Sleek" generally refers to fur or hair being glossy and smooth:

"The new shampoo made her hair shiny and sleek."

It is listed as a variant of slick in verb form: One can "sleek" his/her hair back or one can "slick" his/her hair back. I'd say "slick" is more commonly used as the verb.

"Slick" generally refers to "slicking" one's hair back as I said or it can mean slippery:

"The road was slick with ice."

A coating of oil on water is referred to as an "oil slick." Also, "slick" can be a term for someone who is shrewd or sly.

I'd agree with which mjd writes. Perhaps you should write to the edittors of the Cambridge Dictionary and Dictionary.com, mjd.

"These cars are specially made to emit less pollution." [omit that 'be']

Ok, thanks a lot mjd. That helped. Tricky usage.

[quote]"slick" can be a term for someone who is shrewd or sly.[/quote]

So, only slick can be used to mean someone sly but not sleek, o.k.