Adjective

(en adjective)

Delayed; delayed in development, hindered; impeded.

* 2004 , Duncan Mackay, The Observer , 8 Aug 2004:

HGH, which was originally developed to assist children with retarded growth, is believed to be especially popular with sprinters.

(chiefly, North America) Underdeveloped (of a person's intelligence, abilities etc.).

* 2000 , Kate Connolly, The Guardian , 19 Apr 2000:

The European Roma Rights Centre in Budapest, which is representing the children - from the north-eastern city of Ostrava - said that the education ministry and local authorities had for decades "perpetuated a system which routinely brands disproportionate numbers of Gypsies as mentally retarded ".

(colloquial, derogatory) Stupid, dumb.

* 1988 , Raymond E Feist, Faerie Tale :

Looking at Jack, Gabbie said, "What?" "That's the Troll Bridge." She groaned at the pun. "That's retarded ."

(physics) Designating a parameter of an electromagnetic field which is adjusted to account for the finite speed of radiation.

Adjective

(er)

Taking a long time to move or go a short distance, or to perform an action; not quick in motion; proceeding at a low speed.

* {{quote-magazine, date=2013-07-20, volume=408, issue=8845, magazine=(The Economist)

, title= The attack of the MOOCs , passage=Dotcom mania was slow in coming to higher education, but now it has the venerable industry firmly in its grip. Since the launch early last year of Udacity and Coursera, two Silicon Valley start-ups offering free education through MOOCs, massive open online courses, the ivory towers of academia have been shaken to their foundations.}}

Not happening in a short time; spread over a comparatively long time.

* (John Milton)

These changes in the heavens, though slow , produced / Like change on sea and land, sidereal blast.

* {{quote-magazine, year=2013, month=May-June, author= Charles T. Ambrose

, title= Alzheimer’s Disease , volume=101, issue=3, page=200, magazine=(American Scientist) , passage=Similar studies of rats have employed four different intracranial resorbable, slow sustained release systems—surgical foam, a thermal gel depot, a microcapsule or biodegradable polymer beads.}}

Of reduced intellectual capacity; not quick to comprehend.

Not hasty; not precipitate; lacking in promptness; acting with deliberation.

* The Bible, Prov. xiv. 29

He that is slow to wrath is of great understanding.

(of a clock or the like) Behind]] in time; indicating a time [[early, earlier than the true time.

Lacking spirit; deficient in liveliness or briskness.

(of a period of time) Not busy; lacking activity.