To help keep your writing crisp and precise, observe the distinctions between each pair of similar or closely associated words below:
1. admission/admittance: Admission is the act of being admitted, or allowed to join or enter; admittance is almost identical in meaning but is usually associated with permission (or lack thereof).
2. avocation/vocation: An avocation is a hobby or pursuit, as distinct from a vocation job or career. The former is derived from a word with the literal meaning of “called away,” and the latter is an antonym; it literally means “calling” and is related to the word voice.
3. bloc/block: Bloc refers to an alliance of people, groups, or countries. It is the French version of block, which may be but seldom is used to refer to the same concept.
4. bonds/bounds: A bond, among other meanings, is a restraint, so it is similar in meaning to bound, which means “extent, or limit” (as in boundary). But they are complementary, not interchangeable; one is bound with bonds.
5. cement/concrete: Technically, cement is the powder that constitutes the base of concrete, so any mass of material formed from a moistened mixture of cement and other ingredients should be referred to as concrete.
6. crevice/crevasse: A crevice is a narrow crack; crevasse, from the French version of the word, is a specific term for a large fissure in the ground or in ice.
7. dilemma/difficulty: A dilemma is a particular type of problem exacerbated by the fact that no solution is satisfactory. (The etymology of the word assumes only two possibilities, but it can apply to any number.) The term sometimes applies to any difficult decision but like many words is best reserved for a usefully distinct meaning.
8. dogma/doctrine: Dogma is employed as a synonym for doctrine especially in religious contexts, but the definition of the latter is “a statement or principle,” and the former often has the connotation of repressively authoritarian, rather than authoritative, opinion. (There’s another distinctive pair of words — the former meaning “absolute” and the latter referring to expertise.)
9. ecology/environment: These words are often used interchangeably, but ecology has the more distinct connotation of a system of interrelationship between an environment and the organisms that inhabit it.
10. elegy/eulogy: An elegy is a sorrowful composition, usually for a person or a personification that is literally or figuratively dead. A eulogy, on the other hand, is a statement of praise for a deceased person.
11. empathy/sympathy: Empathy refers to the action of vicariously experiencing the thoughts and emotions of another, and the capacity for doing so, whereas sympathy is the mere act of consolation or feeling compassion.
12. ethics/morals: Ethics are, collectively, the principles of conduct according to a philosophy of moral behavior. The distinction between the two terms is one of theory as opposed to practice.
13. gamut/gauntlet: A gamut is a range. A gauntlet (or gantlet) is a glove. Confusion between the two unrelated words stems from the fact that you can run either one: To run the gamut is to move along a spectrum of choices; to run the gauntlet is to endure the punishment of literally or figuratively passing through a series of ordeals. (Originally, it referred to a double line of soldiers who rained blows on the victim.)
14. review/revue: The latter word is derived from the French form of the former term, but in the sense of a form of entertainment involving songs, skits, and other performances usually commenting on recent publicized events, only it is applicable. A similar production might be termed something like “The Year in Review,” but a production of musical and/or comical pieces is a revue.
15. tenant/tenet: These terms, unrelated in meaning, do share etymology: Each stems from the Latin word for “to hold,” the same one that is the root of tenacious. But a tenant is a person or other entity that holds property, and a tenet is an idea held to be true.