BTEB SSC Vocational key terms

বাংলা ভাষায় দুটি ধ্বনি বা শব্দের মিলনকে সন্ধি বলে; যেমন বিদ্যা ও আলয় মিলে বিদ্যালয় হয়। এটি স্বরসন্ধি ও ব্যঞ্জনসন্ধি ভাগে বিভক্ত।

একাধিক পদের অর্থ সংক্ষেপ করে একটি নতুন পদ গঠনের প্রক্রিয়াকে সমাস বলে; যেমন রাজার পুত্র = রাজপুত্র। এতে পূর্বপদ ও পরপদ মিলে এক পদ হয়।

বাক্যে ক্রিয়ার সঙ্গে বিশেষ্যের যে সম্পর্ক থাকে তাকে কারক বলে। কর্তা, কর্ম, করণ, সম্প্রদান, অপাদান ও অধিকরণ এই ছয় প্রকার কারক প্রচলিত।

বাক্যে পদগুলোর মধ্যে সম্পর্ক প্রকাশকারী প্রত্যয়কে বিভক্তি বলে; যেমন 'বইটি পড়া হয়' এ '-টি' ও ক্রিয়ার রূপ সম্পর্ক বোঝায়। বিভক্তি শব্দের শেষে যুক্ত হয়।

A synonym is a word that carries nearly the same meaning as another word in a given context, such as begin and start. Choosing correctly depends on register and collocation.

An antonym is a word with an opposite meaning to another, such as hot and cold. Not every word has a true antonym, and graded opposites differ from absolute ones.

A part of speech is a grammatical class of words, such as noun, verb, adjective, adverb, pronoun, preposition, conjunction, and interjection. Membership depends on how a word works in a sentence.

Tense is the verb form that locates an action or state in time, mainly past, present, and future, each with simple, progressive, perfect, and perfect progressive aspects in English.

Voice shows whether the subject performs or receives the action. In active voice the subject acts; in passive voice the object becomes subject and a form of be plus past participle is used.

A collocation is a habitual word partnership that sounds natural to native speakers, such as make a decision rather than do a decision. Correct collocation matters in writing and speaking tests.

An idiom is a fixed expression whose meaning cannot be worked out from its individual words, such as under the weather meaning unwell. Idioms are learned as whole units.

A percentage expresses a number as a fraction of one hundred; 25% equals 25/100 or 0.25. To find a percentage of a quantity, multiply by the rate divided by 100.

A ratio compares two quantities of the same kind by division, written as a:b. It has no units, and equivalent ratios are obtained by multiplying both terms by the same number.

A proportion states that two ratios are equal, as in a:b = c:d. In a direct proportion both quantities increase together; in inverse proportion one falls as the other rises.

Simple interest is money paid only on the original principal, calculated as principal times rate times time divided by one hundred. It does not compound over the period.

Compound interest is interest calculated on the principal plus previously earned interest, so the amount grows faster than under simple interest. It is found using A = P(1 + r/n)^(nt).

In a right-angled triangle the square of the hypotenuse equals the sum of the squares of the other two sides, written a squared plus b squared equals c squared. It is used to find unknown sides.

Area is the size of a two-dimensional surface, measured in square units such as square metres. Common formulas include length times breadth for rectangles and half base times height for triangles.

Volume is the amount of three-dimensional space an object occupies, measured in cubic units. For a cuboid it is length times breadth times height; for a cylinder it is pi times radius squared times height.

A trigonometric ratio relates two sides of a right-angled triangle to an acute angle. Sine is opposite over hypotenuse, cosine is adjacent over hypotenuse, and tangent is opposite over adjacent.

A vector is a quantity having both magnitude and direction, such as displacement or force, and is represented by an arrow. Scalars, by contrast, have magnitude only.

A scalar is a physical quantity described fully by magnitude alone, with no direction, such as mass, time, or temperature. Scalars are added by ordinary arithmetic.

Force is an external push or pull that changes or tends to change a body's state of rest or motion, measured in newtons. Its effect depends on magnitude, direction, and point of application.

Torque is the turning effect of a force about a point or axis, equal to force times perpendicular distance from the axis, measured in newton metres. It causes rotation.

Density is mass per unit volume of a substance, usually expressed in kilograms per cubic metre or grams per cubic centimetre. It explains why some objects float and others sink.

In physics, work is done when a force moves a body along the direction of the force, calculated as force times displacement, measured in joules. No displacement means no work.

Power is the rate of doing work or transferring energy, equal to work divided by time and measured in watts. One watt equals one joule per second.

A mole is the amount of substance containing 6.022 times ten to the power 23 elementary entities, such as atoms or molecules. It links mass in grams to number of particles.

Molar mass is the mass of one mole of a substance in grams per mole, numerically equal to its relative molecular mass. It converts between mass and moles in calculations.

The Avogadro number is 6.022 times ten to the power 23, the count of particles in one mole of any substance. It allows chemists to count atoms and molecules by weighing.

Valency is the combining capacity of an element or radical, expressed as the number of hydrogen atoms or equivalent it can combine with. It guides writing correct chemical formulas.

A chemical formula shows the kinds and numbers of atoms in a compound using element symbols and subscripts, such as H2O. It is written using correct valencies and balanced charges.

A balanced equation has equal numbers of each kind of atom on both sides, satisfying conservation of mass. Coefficients are adjusted, never subscripts, to achieve balance.

pH is a scale from 0 to 14 measuring hydrogen ion concentration, where 7 is neutral, below 7 acidic, and above 7 basic. Each unit represents a tenfold change in concentration.

An acid is a substance that releases hydrogen ions in water, turns blue litmus red, and reacts with bases to form salt and water. Common examples include hydrochloric and sulfuric acid.

A base is a substance that accepts hydrogen ions or releases hydroxide ions in water, turns red litmus blue, and neutralises acids. Soluble bases are called alkalis.

In trade work, tolerance is the permitted variation from a specified dimension or value. Parts within tolerance still function correctly, keeping production economical without sacrificing fit.

A vernier caliper is a measuring instrument with a main scale and sliding vernier scale used to measure internal, external, and depth dimensions, typically to 0.02 millimetre accuracy.

A micrometer is a precision measuring instrument using a calibrated screw to measure small thicknesses or diameters, commonly to 0.01 millimetre. The reading combines barrel and thimble scales.

Lockout tagout is a safety procedure that isolates energy sources and attaches locks and warning tags before maintenance, preventing accidental start-up or release of stored energy.

Personal protective equipment is wearable gear such as helmets, gloves, goggles, and safety shoes that reduces exposure to hazards. It is the last line of defence after other controls.

Risk assessment is the process of identifying hazards, judging how likely and how severe harm could be, and deciding controls. It is reviewed whenever work conditions change.