One Word Substitution

Pathology is the branch of medicine that studies the nature, causes, and development of disease through examination of organs, tissues, and bodily fluids. 'Pathos' means disease or suffering, and '-ology' means the study of. The other options are unrelated - plaate is misspelled, ascetic relates to self-denial, and synonyms are words with same meanings.

A pedagogue is a person who is involved in teaching or education. The term comes from Greek 'paidagōgos' meaning a slave who accompanied children to school. It is the correct one-word substitute for a school teacher.

Sophism originated from Greece.It implies any person practicing clever, specious reasoning.

While 'Historian' is a plausible answer, it is a broad term. Someone specifically studying the development of mankind would more precisely be an 'Anthropologist'. However, among the given options, Historian is the closest match as the other options (Oblique, Thing, Botany) are clearly incorrect.

Altur means others and ism means thinking. Thus, altruist is a person who thinks or cares for others. 

Erudite means characterized by great knowledge and learning. It is the perfect one-word substitute for a person believed to be characterized by great knowledge. The word comes from Latin 'eruditus' meaning educated or learned.

Convivialist refers to a person who is jovial and fond of festivities and social gatherings. The term comes from 'convivial' which means friendly and enjoying social gatherings. It is the correct one-word substitute for the given phrase.

Pesticide is the correct term for a chemical substance used to kill insects, especially those that damage crops or spread disease. The other options are unrelated - delete means to remove, feet are body parts, and fool refers to a foolish person.

Anesthesia is the medical term for a substance that blocks sensation, making patients unconscious or insensitive to pain during surgery. The distractors are unrelated - bloody describes appearance, zoo is an animal park, and old refers to age.

An empiric is a person who emphasizes observation and practical experience over theoretical principles in acquiring knowledge. The prefix 'empiric-' relates to empirical (based on observation/experience) rather than theoretical approaches.

Meticulous perfectly describes someone who pays extreme attention to small details and is very careful and precise in their work. The other options are completely irrelevant - theist believes in God, feet are body parts, and fool means a foolish person.

Synonym is the linguistic term for two different words that share the same or similar meanings, like 'happy' and 'joyful.' The other options don't fit - silent means quiet, duplicate means exact copy, and old refers to age.

Centipedes are multi-legged arthropods whose name literally means 'hundred feet' in Latin, though they actually have between 30 and 354 legs depending on the species. The other options are nonsensical - house and stable are buildings, and thing is a generic term.

Improbable correctly describes something that has a low chance of occurring or being true, like winning a lottery twice or snowing in July in the tropics. The other options don't make sense - allergic refers to immune reaction, zoo is an animal park, and thing is too generic.

 A bigot is someone who is prejudiced and generally intolerant of people because of race, ethnicity or religion.

Misogamy is the specific term for strong dislike or hatred of marriage as an institution. The prefix 'miso-' means hatred, like in 'misogyny' (hatred of women). The distractors are unrelated - brittle means easily broken, theist believes in God, atheist disbelieves in God.

Democracy is a system where citizens hold power either directly or through elected representatives - exactly what Lincoln's famous phrase 'of the people, by the people, for the people' means. Monarchy is rule by a king/queen (opposite), educible means capable of being drawn out, and gourmets are food connoisseurs.

Egoist refers to someone who is excessively self-centered and concerned only with their own interests and well-being. 'Ego' means 'I' in Latin, so egoism puts oneself first. Sceptic doubts claims, edible means can be eaten, and expiate means to atone for sins.

Unsociable accurately describes someone who prefers to avoid social interactions and doesn't mix freely with others. Widow is a woman whose spouse died, old refers to age, and park is a public garden - none fit the meaning.

Sadist is the psychological term for someone who enjoys being cruel or inflicting pain on others, named after the Marquis de Sade. Egotism is excessive self-centeredness (a noun, not a person), expiate means to make amends for guilt, and zoo is irrelevant.

Portable means capable of being easily carried or moved. The suffix '-able' in portable indicates the capability or capacity for something. Other options like Park (a place), Old (describing age), and Zoo (a place with animals) do not relate to the ability to carry something.

Honorarium refers to a voluntary payment given to a professional person for services for which fees are not legally or traditionally required. It's distinct from a regular fee or salary. 'Honoured' means respected, 'Stoic' refers to someone indifferent to pleasure or pain, and 'Aid money' refers to financial assistance.

An atheist is a person who does not believe in the existence of God or gods. The prefix 'a-' means 'without' or 'not', and 'theist' refers to belief in god(s). 'Stale' refers to something old or spoiled, 'Honorary' means given as an honour without usual requirements, and 'House' is a dwelling place.

A narcotic is a drug that produces sleep, stupor, insensibility, or torpor. Narcotics act on the central nervous system to depress its activity. 'Gratis' means free of charge, 'Wait' means to remain inactive, and 'Park' refers to a place or to leave a vehicle.

A vegetarian is a person who eats only vegetables and abstains from meat of animals. The word comes from 'vegetable' plus the suffix '-arian' indicating a person who practices something. 'Ductile' means capable of being drawn out into wire, while 'Park' and 'Zoo' are unrelated places.