A vascular cushion of the anal canal; symptomatic bleeding, enlargement or prolapse constitutes haemorrhoidal disease.

Surgical removal of symptomatic haemorrhoidal tissue. It differs from methods that shrink or interrupt blood flow to the tissue without excision.^[ref]

Abnormal narrowing of the anal canal. Scar formation or other structural change can impede evacuation, connecting a local anatomical restriction with altered bowel function.

Passage of blood from the anus. The apparent outlet does not establish the exact site of origin, and a common benign explanation should not be inferred solely from blood color.^[ref]

Morse code encodes characters using short and long signals, conventionally dots and dashes, together with timed gaps. In International Morse code, a dash lasts three dot units; gaps within a character last one unit, between characters three, and between words seven. Thus character boundaries are part of the encoding.

For example, $S$ is three dots and $O$ is three dashes. If gaps are erased, the dot-dash strings alone are not a prefix code: the code for $E$, one dot, is a prefix of that for $I$, two dots. This makes Morse code a useful example of how a communication code can rely on timing as well as symbol choices.^[ref]

A mass formed through coagulation and cellular interactions that can limit bleeding. A clot formed within an intact vessel can instead obstruct flow, connecting the same protective machinery with thrombosis.

A programming closure whose defining semantic environment contains a binding for that same programming closure. In a host with lazy evaluation, this can be represented by a recursive data definition without first running the function's body.

An antifungal drug inhibits fungal growth or damages fungal cells. Different classes act on membrane sterols, cell-wall synthesis or cell division. The target helps explain both the range of susceptible organisms and limits of selectivity.^[ref]

An antiemetic reduces or prevents vomiting. Different drugs act on different sensory and central pathways contributing to the response. A common clinical effect does not establish a single shared receptor mechanism.

A nonsteroidal anti-inflammatory drug is a drug in the group including ibuprofen, naproxen and aspirin. These agents commonly reduce prostaglandin production through cyclooxygenase inhibition. Their shared pathway does not make their duration, selectivity or other effects identical.

A proton pump inhibitor suppresses gastric acid secretion by inhibiting the gastric proton-potassium transport system. Targeting the final secretory machinery differs from neutralizing acid already present in the stomach.

Immunotherapy modifies or uses immune responses to affect disease. Strategies can enhance a response, suppress it or direct it toward a particular target. The umbrella term therefore does not mean that every treatment simply increases immunity.

An astringent is a substance that produces a tightening or drying effect at a tissue surface, often through interactions with proteins. The historical category describes an observed local effect rather than one chemically uniform drug class.

Assessment and management of the harmful effects of medicines in relation to their proposed use.

A climate statistic calculated over a stated long reference period, conventionally often 30 years. Specify the variable, site, period and averaging procedure; a changing climate makes the choice of baseline consequential.^[ref]

There are exactly four types: the two-sphere, real projective plane, torus, and Klein bottle. Four sides admit three pairings and four direction choices for each pairing. Up to cyclic relabelling, labels are adjacent, $a{a}^{s}b{b}^t$, or alternating, $ab{a}^s{b}^t$. For adjacent labels, the vertex counts for $(s,t)=(-1,-1)$, a mixed-sign pair, and $(1,1)$ are $3,2,1$. For alternating labels they are $1,1,2$. There are two edge classes and one face, so Euler characteristic is $V-1$. Orientability occurs exactly when $s=t=-1$. The classification theorem for surfaces identifies every case, leaving no additional closed surfaces from a square. Examples are $a{a}^{-1}b{b}^{-1}$ for the sphere, $aab{b}^{-1}$ for the projective plane, $ab{a}^{-1}{b}^{-1}$ for the torus and $ab{a}^{-1}b$ for the Klein bottle.

For a closed connected orientable surface, its orientable genus is the number of torus summands in its connected sum classification, with the two-sphere assigned genus zero. The Euler characteristic is $2-2g$, so it determines this number within the orientable family.

For a closed connected nonorientable surface, the crosscap number is the number of real projective plane summands in its connected sum classification. It is at least one, and its Euler characteristic is $2-h$. The projective plane has one crosscap and the Klein bottle has two.

A software class declared to inherit from another software class. In nominal object-oriented programming, subclass relationships commonly induce subtype relationships. Valid behavioral substitution also requires satisfying the parent's observable contract, beyond merely declaring the inheritance.

A suspensory fibre transmitting tension to the crystalline lens. Reduced zonular tension during near ocular accommodation permits the crystalline lens to become more rounded.