special

In American English the adjective special is overwhelmingly more common than especial in all senses: He will be of special help if you can't understand the documentation. The reverse is true of the adverbs; here especially is by far the more common: He will be of great help, especially if you have trouble understanding the documentation. Only when the sense “specifically” is intended is specially more idiomatic: The machine was specially designed for use by a left-handed operator.

In the 20th century, special was used freely as a modifier describing services or accessibility resources for people with disabilities or disabled people's functional needs, and sometimes as a euphemism for disabled to label the people themselves. Most euphemistic language for disabilities and people with disabilities is no longer preferred, and special used in this way may be considered offensive, especially when used to describe a person. The phrase special needs is somewhat more accepted, but is less common than it used to be. Instead, when possible, make reference to the specific disability in question. However, the fixed expression special education is still an official designation in public education and continues to be used, even by speakers who otherwise avoid special and its compounds.

Special, particular, specific refer to something pointed out for attention and consideration. Special means given unusual treatment because of being uncommon: a special sense of a word. Particular implies something selected from the others of its kind and set off from them for attention: a particular variety of orchid. Specific implies plain and unambiguous indication of a particular instance, example, etc.: a specific instance of cowardice.