A region of single-stranded DNA or RNA that can form base pairs between complementary sequences. For example the sequence 5'...GACGTGNNNNNCTGCAC...3' could form a short double-stranded region between the sequences shown while any noncomplementary intervening sequences (shown as N to indicate any nucleotides) would form a single-stranded loop. Also called a "stem and loop" structure or a cruciform structure.

A double-helical region in a single DNA or RNA strand formed by the hydrogen-bonding between adjacent inverse complementary sequences to form a hairpin shaped structure.

A structure in which adjacent segments of DNA or RNA fold together and are stabilized by base pairing, creating a loop of single-strand DNA or RNA

A very tight & slow corner that usually takes a car through a 180-degree change of direction.

A very tight and slow corner, that usually is a bend of more than 100°. The most known examples are 'Grand Hotel' in Monaco en 'La source' in Spa-Francorshamps

Refers to a very tight and slow corner, that usually is a bend of more than 100°.

A pin, usually forked, or of bent wire, for fastening the hair in place, -- used by women.

a double pronged pin used to hold women's hair in place

An ornamental pin used to hold hair in place, in a bun, as a decoration, etc.

a blunt needle in the form of a narrow U to fixate hair into position

a needle -like device used to hold a person's hair in place

U-shaped reinforcing steel used to transfer anchor bolt shear (due to column thrust) to concrete floor mass.

Telephony term that means to send a call back in the direction that it came from. For example, if a call cannot be routed over IP to a gateway that is closer to the target telephone, the call typically is sent back out the local zone, back the way from which it came.

A turn that goes through 180 degrees.

A sharp, 180 degree turn.